What problem does this address?

It's a precedent that post meta fields starting with an underscore are "hidden" and don't show up in the regular Custom Fields UI. Feels like they shouldn't show up in the new Block Bindings UI either:

https://developer.wordpress.org/reference/functions/add_post_meta/#comment-467

What is your proposed solution?

Only show post meta fields that don't start with an underscore.

Related Conversation: #64570 (comment)