Hi,
I had the same issue and it appears that there is a conflict between ACF and Yoast SEO (weird).
When activating Yoast, it throws a warning in the console:
"wp.data.select( 'core/editor' ).getBlocks" is deprecated. Please use "wp.data.select( 'core/block-editor' ).getBlocks" instead.
Everything works fine again when the plugin is disabled.
Here my core / plugins versions:
ACF Pro : 5.9.6
Yoast SEO : 16.4
WP Core : 5.7.2
I guess we’ll have to wait for Yoast to update their plugin…