- Drop support for Internet Explorer 11 (#31110). Learn more at https://make.wordpress.org/core/2021/04/22/ie-11-support-phase-out-plan/.
- Increase the minimum Node.js version to v12 matching Long Term Support releases (#31270). Learn more at https://nodejs.org/en/about/releases/.
- Inner blocks are now cast as arrays instead of objects.
- JS and PHP parsers now behave consistently when parsing empty attributes.
- Add new list of HTML fragments to parse output.
- Optimize JSON-attribute parsing.
- Initial release.