diff --git a/packages/babel-preset-default/CHANGELOG.md b/packages/babel-preset-default/CHANGELOG.md
index 060cc915d5d815..07579a565ac286 100644
--- a/packages/babel-preset-default/CHANGELOG.md
+++ b/packages/babel-preset-default/CHANGELOG.md
@@ -2,6 +2,10 @@
 
 ## Unreleased
 
+## Breaking Changes
+
+- Revert enabling the `shippedProposals` flag. That flag enables the use of stage-3 proposals, but the goal of this preset is to only support stage-4 features. [#22083](https://github.com/WordPress/gutenberg/pull/22083)
+
 ## 4.12.0 (2020-04-15)
 
 ### New Features
diff --git a/packages/babel-preset-default/index.js b/packages/babel-preset-default/index.js
index e331b212cd0ba8..d83c94b2a3b2aa 100644
--- a/packages/babel-preset-default/index.js
+++ b/packages/babel-preset-default/index.js
@@ -16,9 +16,7 @@ module.exports = function( api ) {
 	} );
 
 	const getPresetEnv = () => {
-		const opts = {
-			shippedProposals: true,
-		};
+		const opts = {};
 
 		if ( isTestEnv ) {
 			opts.targets = {
diff --git a/packages/scripts/CHANGELOG.md b/packages/scripts/CHANGELOG.md
index 47043ce3277f19..4851a718685619 100644
--- a/packages/scripts/CHANGELOG.md
+++ b/packages/scripts/CHANGELOG.md
@@ -8,6 +8,10 @@
 - New `--webpack-bundle-analyzer` flag added to `build` and `start` scripts. It enables visualization for the size of webpack output files with an interactive zoomable treemap ([#22310](https://github.com/WordPress/gutenberg/pull/22310)).
 - New `--webpack--devtool` flag added to `start` script. It controls how source maps are generated. See options at https://webpack.js.org/configuration/devtool/#devtool ([#22310](https://github.com/WordPress/gutenberg/pull/22310)).
 
+### Breaking Changes
+
+- The default babel configuration has changed to only support stage-4 proposals. This affects the `build` and `start` commands that use the bundled babel configuration; if a project provides its own, this change doesn't affect it. [#22083](https://github.com/WordPress/gutenberg/pull/22083)
+
 ## 9.1.0 (2020-05-14)
 
 ### Enhancements