Description

After inserting a list block, it appears that the DOM is modified leaving only one button. This makes all other block insert options unreadable to screen reader users and possibly not available for all. I would expect the blocks to still be available no matter what is inserted.

Step-by-step reproduction instructions

1. Open a post or page.
2. Select Toggle block inserter in the top bar.
3. Insert a paragraph block.
4. Verify you can still move around in the inserter with left and right arrows.
5. Navigate to and insert a list block.
6. Notice how focus is lost, this PR is fixing that: Fix focus loss due to filtering blocks #61558. Ignore this for now.
7. Place focus back on the inserter and notice how pressing left and right arrows no longer works to move through your available block selections.

Screenshots, screen recording, code snippet

No response

Environment info

Gutenberg: trunk
WordPress: Latest development
Browser: Firefox on Windows, latest

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