DA + Blocks + Different themes + CKEditor5 is unstable

I'm virtually certain that this is the problematic combination, so I've disabled CKEditor5 for the moment.

Obviously, that's not a long-term solution.

If you use different themes (and block assignments) to control appearance, I think you're likely to experience the same issues I've been having: HTML disappearing on save, blocks not saving, etc.

Having a text editor for blocks wasn't available in Drupal 7 (or I don't recall it being so), so this particular combination probably hasn't been battle-tested. I'm just making a note of it here (for now) to aid in troubleshooting.

Thanks and a Happy 4th to all!