WordPress 7.1 was going to move the block editor to React 19. It is not. Core enabled it in Gutenberg, hit interop problems with plugins and reverted, so 7.1 ships on React 18.3. What happened, what it means if you already migrated, and the change that is now the real compatibility risk.
WordPress 7.1 Beta 1 landed July 15, with the final release August 19. What is in it - AI tooling, collaboration, responsive design, media, and an enforced iframed editor - and exactly how to test your plugins and themes before release day.
WordPress 7.1 was going to move the block editor from React 18 to React 19. It does not: core hit interop problems and reverted, so 7.1 ships on React 18.3. The migration is deferred, not cancelled, and the work to prepare your blocks is unchanged.