Bugfix: SuspenseList incorrectly forces a fallback #26453
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Fixes a bug in SuspenseList that @kassens found when deploying React to Meta. In some scenarios, SuspenseList would force the fallback of a deeply nested Suspense boundary into fallback mode, which should never happen under any circumstances — SuspenseList should only affect the nearest descendent Suspense boundaries, without going deeper. The cause was that the internal ForceSuspenseFallback context flag was not being properly reset when it reached the nearest Suspense boundary. It should only be propagated shallowly. We didn't discover this earlier because the scenario where it happens is not that common. To trigger the bug, you need to insert a new Suspense boundary into an already-mounted row of the list. But often when a new Suspense boundary is rendered, it suspends and shows a fallback, anyway, because its content hasn't loaded yet. Another reason we didn't discover this earlier is because there was another bug that was accidentally masking it, which was fixed by facebook#25922. When that fix landed, it revealed this bug. The SuspenseList implementation is complicated but I'm not too concerned with the current messiness. It's an experimental API, and we intend to release it soon, but there are some known flaws and missing features that we need to address first regardless. We'll likely end up rewriting most of it. Co-Authored-By: Jan Kassens <jkassens@meta.com>
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Fixes a bug in SuspenseList that @kassens found when deploying React to Meta. In some scenarios, SuspenseList would force the fallback of a deeply nested Suspense boundary into fallback mode, which should never happen under any circumstances — SuspenseList should only affect the nearest descendent Suspense boundaries, without going deeper. The cause was that the internal ForceSuspenseFallback context flag was not being properly reset when it reached the nearest Suspense boundary. It should only be propagated shallowly. We didn't discover this earlier because the scenario where it happens is not that common. To trigger the bug, you need to insert a new Suspense boundary into an already-mounted row of the list. But often when a new Suspense boundary is rendered, it suspends and shows a fallback, anyway, because its content hasn't loaded yet. Another reason we didn't discover this earlier is because there was another bug that was accidentally masking it, which was fixed by #25922. When that fix landed, it revealed this bug. The SuspenseList implementation is complicated but I'm not too concerned with the current messiness. It's an experimental API, and we intend to release it soon, but there are some known flaws and missing features that we need to address first regardless. We'll likely end up rewriting most of it. Co-authored-by: Jan Kassens <jkassens@meta.com> DiffTrain build for [51a7c45](51a7c45)
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Summary: This sync includes the following changes: - **[ca01f359b](facebook/react@ca01f359b )**: Remove skipUnmountedBoundaries ([#26489](facebook/react#26489)) //<Ricky>// - **[43a70a610](facebook/react@43a70a610 )**: Limit the meaning of "custom element" to not include `is` ([#26524](facebook/react#26524)) //<Sebastian Markbåge>// - **[1308e49a6](facebook/react@1308e49a6 )**: [Flight Plugin] Scan for "use client" ([#26474](facebook/react#26474)) //<dan>// - **[1a1d61fed](facebook/react@1a1d61fed )**: Warn for ARIA typos on custom elements ([#26523](facebook/react#26523)) //<Sebastian Markbåge>// - **[73deff0d5](facebook/react@73deff0d5 )**: Refactor DOMProperty and CSSProperty ([#26513](facebook/react#26513)) //<Sebastian Markbåge>// - **[2d51251e6](facebook/react@2d51251e6 )**: Clean up deferRenderPhaseUpdateToNextBatch ([#26511](facebook/react#26511)) //<Andrew Clark>// - **[0ffc7f632](facebook/react@0ffc7f632 )**: Update useMemoCache test to confirm that cache persists across errors ([#26510](facebook/react#26510)) //<Joseph Savona>// - **[29a3be78b](facebook/react@29a3be78b )**: Move ReactDOMFloat to react-dom/src/ ([#26514](facebook/react#26514)) //<Sebastian Markbåge>// - **[4c2fc0190](facebook/react@4c2fc0190 )**: Generate safe javascript url instead of throwing with disableJavaScriptURLs is on ([#26507](facebook/react#26507)) //<Sebastian Markbåge>// - **[f0aafa1a7](facebook/react@f0aafa1a7 )**: Convert a few more tests to waitFor test helpers ([#26509](facebook/react#26509)) //<Andrew Clark>// - **[90995ef8b](facebook/react@90995ef8b )**: Delete "triangle" resuming fuzz tester ([#26508](facebook/react#26508)) //<Andrew Clark>// - **[f118b7ceb](facebook/react@f118b7ceb )**: [Flight] Gated test for dropped transport of undefined object values ([#26478](facebook/react#26478)) //<Sebastian Silbermann>// - **[fd0511c72](facebook/react@fd0511c72 )**: [Flight] Add support BigInt support ([#26479](facebook/react#26479)) //<Sebastian Silbermann>// - **[85de6fde5](facebook/react@85de6fde5 )**: Refactor DOM special cases per tags including controlled fields ([#26501](facebook/react#26501)) //<Sebastian Markbåge>// - **[1f5cdf8c7](facebook/react@1f5cdf8c7 )**: Update Suspense fuzz tests to use `act` ([#26498](facebook/react#26498)) //<Andrew Clark>// - **[f62cb39ee](facebook/react@f62cb39ee )**: Make disableSchedulerTimeoutInWorkLoop a static ff ([#26497](facebook/react#26497)) //<Ricky>// - **[41b4714f1](facebook/react@41b4714f1 )**: Remove disableNativeComponentFrames ([#26490](facebook/react#26490)) //<Ricky>// - **[fc90eb636](facebook/react@fc90eb636 )**: Codemod more tests to waitFor pattern ([#26494](facebook/react#26494)) //<Andrew Clark>// - **[e0bbc2662](facebook/react@e0bbc2662 )**: Improve tests that deal with microtasks ([#26493](facebook/react#26493)) //<Andrew Clark>// - **[8faf75193](facebook/react@8faf75193 )**: Codemod some expiration tests to waitForExpired ([#26491](facebook/react#26491)) //<Andrew Clark>// - **[8342a0992](facebook/react@8342a0992 )**: Remove unused feature flag disableSchedulerTimeoutBasedOnReactExpirationTime ([#26488](facebook/react#26488)) //<Jan Kassens>// - **[afea1d0c5](facebook/react@afea1d0c5 )**: [flow] make Flow suppressions explicit on the error ([#26487](facebook/react#26487)) //<Jan Kassens>// - **[768f965de](facebook/react@768f965de )**: Suspensily committing a prerendered tree ([#26434](facebook/react#26434)) //<Andrew Clark>// - **[d12bdcda6](facebook/react@d12bdcda6 )**: Fix Flow types of useEffectEvent ([#26468](facebook/react#26468)) //<Sebastian Silbermann>// - **[73b6435ca](facebook/react@73b6435ca )**: [Float][Fiber] Implement waitForCommitToBeReady for stylesheet resources ([#26450](facebook/react#26450)) //<Josh Story>// - **[175962c10](facebook/react@175962c10 )**: Fix remaining CommonJS imports after Rollup upgrade ([#26473](facebook/react#26473)) //<dan>// - **[909c6dacf](facebook/react@909c6dacf )**: Update Rollup to 3.x ([#26442](facebook/react#26442)) //<Mark Erikson>// - **[9c54b29b4](facebook/react@9c54b29b4 )**: Remove ReactFabricPublicInstance and used definition from ReactNativePrivateInterface ([#26437](facebook/react#26437)) //<Rubén Norte>// - **[f77099b6f](facebook/react@f77099b6f )**: Remove layout effect warning on the server ([#26395](facebook/react#26395)) //<Ricky>// - **[51a7c45f8](facebook/react@51a7c45f8 )**: Bugfix: SuspenseList incorrectly forces a fallback ([#26453](facebook/react#26453)) //<Andrew Clark>// - **[afb3d51dc](facebook/react@afb3d51dc )**: Fix enableClientRenderFallbackOnTextMismatch flag ([#26457](facebook/react#26457)) //<Sebastian Markbåge>// - **[8e17bfd14](facebook/react@8e17bfd14 )**: Make InternalInstanceHandle type opaque in ReactNativeTypes ([#26461](facebook/react#26461)) //<Rubén Norte>// - **[b93b4f074](facebook/react@b93b4f074 )**: Should not throw for children of iframe or object ([#26458](facebook/react#26458)) //<Sebastian Markbåge>// - **[c0b34bc5f](facebook/react@c0b34bc5f )**: chore: update links of docs and api ([#26455](facebook/react#26455)) //<Leedom>// - **[ffb6733ee](facebook/react@ffb6733ee )**: fix docs link for useSyncExternalStore ([#26452](facebook/react#26452)) //<Valor(华洛)>// - **[12a1d140e](facebook/react@12a1d140e )**: Don't prerender siblings of suspended component ([#26380](facebook/react#26380)) //<Andrew Clark>// Changelog: [General][Changed] - React Native sync for revisions 77ba161...ca01f35 jest_e2e[run_all_tests] bypass-github-export-checks Reviewed By: sammy-SC Differential Revision: D44669450 fbshipit-source-id: f160aad4719a00df3ceeca78d5f3fcd0aa0f8437
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Summary: This sync includes the following changes: - **[ca01f359b](facebook/react@ca01f359b )**: Remove skipUnmountedBoundaries ([facebook#26489](facebook/react#26489)) //<Ricky>// - **[43a70a610](facebook/react@43a70a610 )**: Limit the meaning of "custom element" to not include `is` ([facebook#26524](facebook/react#26524)) //<Sebastian Markbåge>// - **[1308e49a6](facebook/react@1308e49a6 )**: [Flight Plugin] Scan for "use client" ([facebook#26474](facebook/react#26474)) //<dan>// - **[1a1d61fed](facebook/react@1a1d61fed )**: Warn for ARIA typos on custom elements ([facebook#26523](facebook/react#26523)) //<Sebastian Markbåge>// - **[73deff0d5](facebook/react@73deff0d5 )**: Refactor DOMProperty and CSSProperty ([facebook#26513](facebook/react#26513)) //<Sebastian Markbåge>// - **[2d51251e6](facebook/react@2d51251e6 )**: Clean up deferRenderPhaseUpdateToNextBatch ([facebook#26511](facebook/react#26511)) //<Andrew Clark>// - **[0ffc7f632](facebook/react@0ffc7f632 )**: Update useMemoCache test to confirm that cache persists across errors ([facebook#26510](facebook/react#26510)) //<Joseph Savona>// - **[29a3be78b](facebook/react@29a3be78b )**: Move ReactDOMFloat to react-dom/src/ ([facebook#26514](facebook/react#26514)) //<Sebastian Markbåge>// - **[4c2fc0190](facebook/react@4c2fc0190 )**: Generate safe javascript url instead of throwing with disableJavaScriptURLs is on ([facebook#26507](facebook/react#26507)) //<Sebastian Markbåge>// - **[f0aafa1a7](facebook/react@f0aafa1a7 )**: Convert a few more tests to waitFor test helpers ([facebook#26509](facebook/react#26509)) //<Andrew Clark>// - **[90995ef8b](facebook/react@90995ef8b )**: Delete "triangle" resuming fuzz tester ([facebook#26508](facebook/react#26508)) //<Andrew Clark>// - **[f118b7ceb](facebook/react@f118b7ceb )**: [Flight] Gated test for dropped transport of undefined object values ([facebook#26478](facebook/react#26478)) //<Sebastian Silbermann>// - **[fd0511c72](facebook/react@fd0511c72 )**: [Flight] Add support BigInt support ([facebook#26479](facebook/react#26479)) //<Sebastian Silbermann>// - **[85de6fde5](facebook/react@85de6fde5 )**: Refactor DOM special cases per tags including controlled fields ([facebook#26501](facebook/react#26501)) //<Sebastian Markbåge>// - **[1f5cdf8c7](facebook/react@1f5cdf8c7 )**: Update Suspense fuzz tests to use `act` ([facebook#26498](facebook/react#26498)) //<Andrew Clark>// - **[f62cb39ee](facebook/react@f62cb39ee )**: Make disableSchedulerTimeoutInWorkLoop a static ff ([facebook#26497](facebook/react#26497)) //<Ricky>// - **[41b4714f1](facebook/react@41b4714f1 )**: Remove disableNativeComponentFrames ([facebook#26490](facebook/react#26490)) //<Ricky>// - **[fc90eb636](facebook/react@fc90eb636 )**: Codemod more tests to waitFor pattern ([facebook#26494](facebook/react#26494)) //<Andrew Clark>// - **[e0bbc2662](facebook/react@e0bbc2662 )**: Improve tests that deal with microtasks ([facebook#26493](facebook/react#26493)) //<Andrew Clark>// - **[8faf75193](facebook/react@8faf75193 )**: Codemod some expiration tests to waitForExpired ([facebook#26491](facebook/react#26491)) //<Andrew Clark>// - **[8342a0992](facebook/react@8342a0992 )**: Remove unused feature flag disableSchedulerTimeoutBasedOnReactExpirationTime ([facebook#26488](facebook/react#26488)) //<Jan Kassens>// - **[afea1d0c5](facebook/react@afea1d0c5 )**: [flow] make Flow suppressions explicit on the error ([facebook#26487](facebook/react#26487)) //<Jan Kassens>// - **[768f965de](facebook/react@768f965de )**: Suspensily committing a prerendered tree ([facebook#26434](facebook/react#26434)) //<Andrew Clark>// - **[d12bdcda6](facebook/react@d12bdcda6 )**: Fix Flow types of useEffectEvent ([facebook#26468](facebook/react#26468)) //<Sebastian Silbermann>// - **[73b6435ca](facebook/react@73b6435ca )**: [Float][Fiber] Implement waitForCommitToBeReady for stylesheet resources ([facebook#26450](facebook/react#26450)) //<Josh Story>// - **[175962c10](facebook/react@175962c10 )**: Fix remaining CommonJS imports after Rollup upgrade ([facebook#26473](facebook/react#26473)) //<dan>// - **[909c6dacf](facebook/react@909c6dacf )**: Update Rollup to 3.x ([facebook#26442](facebook/react#26442)) //<Mark Erikson>// - **[9c54b29b4](facebook/react@9c54b29b4 )**: Remove ReactFabricPublicInstance and used definition from ReactNativePrivateInterface ([facebook#26437](facebook/react#26437)) //<Rubén Norte>// - **[f77099b6f](facebook/react@f77099b6f )**: Remove layout effect warning on the server ([facebook#26395](facebook/react#26395)) //<Ricky>// - **[51a7c45f8](facebook/react@51a7c45f8 )**: Bugfix: SuspenseList incorrectly forces a fallback ([facebook#26453](facebook/react#26453)) //<Andrew Clark>// - **[afb3d51dc](facebook/react@afb3d51dc )**: Fix enableClientRenderFallbackOnTextMismatch flag ([facebook#26457](facebook/react#26457)) //<Sebastian Markbåge>// - **[8e17bfd14](facebook/react@8e17bfd14 )**: Make InternalInstanceHandle type opaque in ReactNativeTypes ([facebook#26461](facebook/react#26461)) //<Rubén Norte>// - **[b93b4f074](facebook/react@b93b4f074 )**: Should not throw for children of iframe or object ([facebook#26458](facebook/react#26458)) //<Sebastian Markbåge>// - **[c0b34bc5f](facebook/react@c0b34bc5f )**: chore: update links of docs and api ([facebook#26455](facebook/react#26455)) //<Leedom>// - **[ffb6733ee](facebook/react@ffb6733ee )**: fix docs link for useSyncExternalStore ([facebook#26452](facebook/react#26452)) //<Valor(华洛)>// - **[12a1d140e](facebook/react@12a1d140e )**: Don't prerender siblings of suspended component ([facebook#26380](facebook/react#26380)) //<Andrew Clark>// Changelog: [General][Changed] - React Native sync for revisions 77ba161...ca01f35 jest_e2e[run_all_tests] bypass-github-export-checks Reviewed By: sammy-SC Differential Revision: D44669450 fbshipit-source-id: f160aad4719a00df3ceeca78d5f3fcd0aa0f8437
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May 22, 2023
Summary: This sync includes the following changes: - **[ca01f359b](facebook/react@ca01f359b )**: Remove skipUnmountedBoundaries ([facebook#26489](facebook/react#26489)) //<Ricky>// - **[43a70a610](facebook/react@43a70a610 )**: Limit the meaning of "custom element" to not include `is` ([facebook#26524](facebook/react#26524)) //<Sebastian Markbåge>// - **[1308e49a6](facebook/react@1308e49a6 )**: [Flight Plugin] Scan for "use client" ([facebook#26474](facebook/react#26474)) //<dan>// - **[1a1d61fed](facebook/react@1a1d61fed )**: Warn for ARIA typos on custom elements ([facebook#26523](facebook/react#26523)) //<Sebastian Markbåge>// - **[73deff0d5](facebook/react@73deff0d5 )**: Refactor DOMProperty and CSSProperty ([facebook#26513](facebook/react#26513)) //<Sebastian Markbåge>// - **[2d51251e6](facebook/react@2d51251e6 )**: Clean up deferRenderPhaseUpdateToNextBatch ([facebook#26511](facebook/react#26511)) //<Andrew Clark>// - **[0ffc7f632](facebook/react@0ffc7f632 )**: Update useMemoCache test to confirm that cache persists across errors ([facebook#26510](facebook/react#26510)) //<Joseph Savona>// - **[29a3be78b](facebook/react@29a3be78b )**: Move ReactDOMFloat to react-dom/src/ ([facebook#26514](facebook/react#26514)) //<Sebastian Markbåge>// - **[4c2fc0190](facebook/react@4c2fc0190 )**: Generate safe javascript url instead of throwing with disableJavaScriptURLs is on ([facebook#26507](facebook/react#26507)) //<Sebastian Markbåge>// - **[f0aafa1a7](facebook/react@f0aafa1a7 )**: Convert a few more tests to waitFor test helpers ([facebook#26509](facebook/react#26509)) //<Andrew Clark>// - **[90995ef8b](facebook/react@90995ef8b )**: Delete "triangle" resuming fuzz tester ([facebook#26508](facebook/react#26508)) //<Andrew Clark>// - **[f118b7ceb](facebook/react@f118b7ceb )**: [Flight] Gated test for dropped transport of undefined object values ([facebook#26478](facebook/react#26478)) //<Sebastian Silbermann>// - **[fd0511c72](facebook/react@fd0511c72 )**: [Flight] Add support BigInt support ([facebook#26479](facebook/react#26479)) //<Sebastian Silbermann>// - **[85de6fde5](facebook/react@85de6fde5 )**: Refactor DOM special cases per tags including controlled fields ([facebook#26501](facebook/react#26501)) //<Sebastian Markbåge>// - **[1f5cdf8c7](facebook/react@1f5cdf8c7 )**: Update Suspense fuzz tests to use `act` ([facebook#26498](facebook/react#26498)) //<Andrew Clark>// - **[f62cb39ee](facebook/react@f62cb39ee )**: Make disableSchedulerTimeoutInWorkLoop a static ff ([facebook#26497](facebook/react#26497)) //<Ricky>// - **[41b4714f1](facebook/react@41b4714f1 )**: Remove disableNativeComponentFrames ([facebook#26490](facebook/react#26490)) //<Ricky>// - **[fc90eb636](facebook/react@fc90eb636 )**: Codemod more tests to waitFor pattern ([facebook#26494](facebook/react#26494)) //<Andrew Clark>// - **[e0bbc2662](facebook/react@e0bbc2662 )**: Improve tests that deal with microtasks ([facebook#26493](facebook/react#26493)) //<Andrew Clark>// - **[8faf75193](facebook/react@8faf75193 )**: Codemod some expiration tests to waitForExpired ([facebook#26491](facebook/react#26491)) //<Andrew Clark>// - **[8342a0992](facebook/react@8342a0992 )**: Remove unused feature flag disableSchedulerTimeoutBasedOnReactExpirationTime ([facebook#26488](facebook/react#26488)) //<Jan Kassens>// - **[afea1d0c5](facebook/react@afea1d0c5 )**: [flow] make Flow suppressions explicit on the error ([facebook#26487](facebook/react#26487)) //<Jan Kassens>// - **[768f965de](facebook/react@768f965de )**: Suspensily committing a prerendered tree ([facebook#26434](facebook/react#26434)) //<Andrew Clark>// - **[d12bdcda6](facebook/react@d12bdcda6 )**: Fix Flow types of useEffectEvent ([facebook#26468](facebook/react#26468)) //<Sebastian Silbermann>// - **[73b6435ca](facebook/react@73b6435ca )**: [Float][Fiber] Implement waitForCommitToBeReady for stylesheet resources ([facebook#26450](facebook/react#26450)) //<Josh Story>// - **[175962c10](facebook/react@175962c10 )**: Fix remaining CommonJS imports after Rollup upgrade ([facebook#26473](facebook/react#26473)) //<dan>// - **[909c6dacf](facebook/react@909c6dacf )**: Update Rollup to 3.x ([facebook#26442](facebook/react#26442)) //<Mark Erikson>// - **[9c54b29b4](facebook/react@9c54b29b4 )**: Remove ReactFabricPublicInstance and used definition from ReactNativePrivateInterface ([facebook#26437](facebook/react#26437)) //<Rubén Norte>// - **[f77099b6f](facebook/react@f77099b6f )**: Remove layout effect warning on the server ([facebook#26395](facebook/react#26395)) //<Ricky>// - **[51a7c45f8](facebook/react@51a7c45f8 )**: Bugfix: SuspenseList incorrectly forces a fallback ([facebook#26453](facebook/react#26453)) //<Andrew Clark>// - **[afb3d51dc](facebook/react@afb3d51dc )**: Fix enableClientRenderFallbackOnTextMismatch flag ([facebook#26457](facebook/react#26457)) //<Sebastian Markbåge>// - **[8e17bfd14](facebook/react@8e17bfd14 )**: Make InternalInstanceHandle type opaque in ReactNativeTypes ([facebook#26461](facebook/react#26461)) //<Rubén Norte>// - **[b93b4f074](facebook/react@b93b4f074 )**: Should not throw for children of iframe or object ([facebook#26458](facebook/react#26458)) //<Sebastian Markbåge>// - **[c0b34bc5f](facebook/react@c0b34bc5f )**: chore: update links of docs and api ([facebook#26455](facebook/react#26455)) //<Leedom>// - **[ffb6733ee](facebook/react@ffb6733ee )**: fix docs link for useSyncExternalStore ([facebook#26452](facebook/react#26452)) //<Valor(华洛)>// - **[12a1d140e](facebook/react@12a1d140e )**: Don't prerender siblings of suspended component ([facebook#26380](facebook/react#26380)) //<Andrew Clark>// Changelog: [General][Changed] - React Native sync for revisions 77ba161...ca01f35 jest_e2e[run_all_tests] bypass-github-export-checks Reviewed By: sammy-SC Differential Revision: D44669450 fbshipit-source-id: f160aad4719a00df3ceeca78d5f3fcd0aa0f8437
bigfootjon
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Fixes a bug in SuspenseList that @kassens found when deploying React to Meta. In some scenarios, SuspenseList would force the fallback of a deeply nested Suspense boundary into fallback mode, which should never happen under any circumstances — SuspenseList should only affect the nearest descendent Suspense boundaries, without going deeper. The cause was that the internal ForceSuspenseFallback context flag was not being properly reset when it reached the nearest Suspense boundary. It should only be propagated shallowly. We didn't discover this earlier because the scenario where it happens is not that common. To trigger the bug, you need to insert a new Suspense boundary into an already-mounted row of the list. But often when a new Suspense boundary is rendered, it suspends and shows a fallback, anyway, because its content hasn't loaded yet. Another reason we didn't discover this earlier is because there was another bug that was accidentally masking it, which was fixed by #25922. When that fix landed, it revealed this bug. The SuspenseList implementation is complicated but I'm not too concerned with the current messiness. It's an experimental API, and we intend to release it soon, but there are some known flaws and missing features that we need to address first regardless. We'll likely end up rewriting most of it. Co-authored-by: Jan Kassens <jkassens@meta.com> DiffTrain build for commit 51a7c45.
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Fixes a bug in SuspenseList that @kassens found when deploying React to Meta. In some scenarios, SuspenseList would force the fallback of a deeply nested Suspense boundary into fallback mode, which should never happen under any circumstances — SuspenseList should only affect the nearest descendent Suspense boundaries, without going deeper.
The cause was that the internal ForceSuspenseFallback context flag was not being properly reset when it reached the nearest Suspense boundary. It should only be propagated shallowly.
We didn't discover this earlier because the scenario where it happens is not that common. To trigger the bug, you need to insert a new Suspense boundary into an already-mounted row of the list. But often when a new Suspense boundary is rendered, it suspends and shows a fallback, anyway, because its content hasn't loaded yet.
Another reason we didn't discover this earlier is because there was another bug that was accidentally masking it, which was fixed by #25922. When that fix landed, it revealed this bug.
The SuspenseList implementation is complicated but I'm not too concerned with the current messiness. It's an experimental API, and we intend to release it soon, but there are some known flaws and missing features that we need to address first regardless. We'll likely end up rewriting most of it.