Description

As reported by @gziolo here:

One thing that might need closer look is when using the Classic block in the post content. I couldn't make it work with inserting the hooked block as the last or first child in the core/post-content block.

Step-by-step reproduction instructions

TBD

Screenshots, screen recording, code snippet

Environment info

No response

Please confirm that you have searched existing issues in the repo.

• Yes

Please confirm that you have tested with all plugins deactivated except Gutenberg.

• Yes

Please confirm which theme type you used for testing.

• Block
• Classic
• Hybrid (e.g. classic with theme.json)
• Not sure