diff --git a/packages/react-reconciler/src/ReactFiberBeginWork.js b/packages/react-reconciler/src/ReactFiberBeginWork.js
index 1b0b6b8d97310..372bab95cea57 100644
--- a/packages/react-reconciler/src/ReactFiberBeginWork.js
+++ b/packages/react-reconciler/src/ReactFiberBeginWork.js
@@ -2033,7 +2033,7 @@ function mountLazyComponent(
 
   if (typeof Component === 'function') {
     if (isFunctionClassComponent(Component)) {
-      const resolvedProps = resolveClassComponentProps(Component, props, false);
+      const resolvedProps = resolveClassComponentProps(Component, props);
       workInProgress.tag = ClassComponent;
       if (__DEV__) {
         workInProgress.type = Component =
@@ -4134,7 +4134,6 @@ function beginWork(
       const resolvedProps = resolveClassComponentProps(
         Component,
         unresolvedProps,
-        workInProgress.elementType === Component,
       );
       return updateClassComponent(
         current,
@@ -4210,7 +4209,6 @@ function beginWork(
       const resolvedProps = resolveClassComponentProps(
         Component,
         unresolvedProps,
-        workInProgress.elementType === Component,
       );
       return mountIncompleteClassComponent(
         current,
@@ -4229,7 +4227,6 @@ function beginWork(
       const resolvedProps = resolveClassComponentProps(
         Component,
         unresolvedProps,
-        workInProgress.elementType === Component,
       );
       return mountIncompleteFunctionComponent(
         current,
diff --git a/packages/react-reconciler/src/ReactFiberClassComponent.js b/packages/react-reconciler/src/ReactFiberClassComponent.js
index 7a9b443b3c282..22a80d8dbe977 100644
--- a/packages/react-reconciler/src/ReactFiberClassComponent.js
+++ b/packages/react-reconciler/src/ReactFiberClassComponent.js
@@ -858,11 +858,7 @@ function resumeMountClassInstance(
   const instance = workInProgress.stateNode;
 
   const unresolvedOldProps = workInProgress.memoizedProps;
-  const oldProps = resolveClassComponentProps(
-    ctor,
-    unresolvedOldProps,
-    workInProgress.type === workInProgress.elementType,
-  );
+  const oldProps = resolveClassComponentProps(ctor, unresolvedOldProps);
   instance.props = oldProps;
 
   const oldContext = instance.context;
@@ -1017,11 +1013,7 @@ function updateClassInstance(
   cloneUpdateQueue(current, workInProgress);
 
   const unresolvedOldProps = workInProgress.memoizedProps;
-  const oldProps = resolveClassComponentProps(
-    ctor,
-    unresolvedOldProps,
-    workInProgress.type === workInProgress.elementType,
-  );
+  const oldProps = resolveClassComponentProps(ctor, unresolvedOldProps);
   instance.props = oldProps;
   const unresolvedNewProps = workInProgress.pendingProps;
 
@@ -1192,12 +1184,6 @@ function updateClassInstance(
 export function resolveClassComponentProps(
   Component: any,
   baseProps: Object,
-  // Only resolve default props if this is a lazy component. Otherwise, they
-  // would have already been resolved by the JSX runtime.
-  // TODO: We're going to remove default prop resolution from the JSX runtime
-  // and keep it only for class components. As part of that change, we should
-  // remove this extra check.
-  alreadyResolvedDefaultProps: boolean,
 ): Object {
   let newProps = baseProps;
 
diff --git a/packages/react-reconciler/src/ReactFiberCommitEffects.js b/packages/react-reconciler/src/ReactFiberCommitEffects.js
index 6dbeb81078842..f7e20fe926193 100644
--- a/packages/react-reconciler/src/ReactFiberCommitEffects.js
+++ b/packages/react-reconciler/src/ReactFiberCommitEffects.js
@@ -410,7 +410,6 @@ export function commitClassLayoutLifecycles(
     const prevProps = resolveClassComponentProps(
       finishedWork.type,
       current.memoizedProps,
-      finishedWork.elementType === finishedWork.type,
     );
     const prevState = current.memoizedState;
     // We could update instance props and state here,
@@ -671,7 +670,6 @@ export function commitClassSnapshot(finishedWork: Fiber, current: Fiber) {
     const resolvedPrevProps = resolveClassComponentProps(
       finishedWork.type,
       prevProps,
-      finishedWork.elementType === finishedWork.type,
     );
     let snapshot;
     if (__DEV__) {
@@ -716,7 +714,6 @@ export function safelyCallComponentWillUnmount(
   instance.props = resolveClassComponentProps(
     current.type,
     current.memoizedProps,
-    current.elementType === current.type,
   );
   instance.state = current.memoizedState;
   if (shouldProfile(current)) {