Advanced Settings collapsible button overlaps with panel title
The Advanced Settings title and button overlap in the editor:
Adding a top margin to .crx-collapsible > button resolves the issue (but I don't know if that's the kind of fix you'd prefer).
I'm seeing this in Wagtail 7.1.1 with CRX 6. Changes to collapsible block settings were part of the upgrades for Wagtail 7.1, so maybe that's related.
Thanks for reporting. I believe we always had to intentionally overlap them to "hide" the wagtail label in favor of our button. One of the few remaining hacks we have in the wagtail admin. So adjusting the margin/placement of the button is necessary to overlap the label.
However, the new collapsible block settings seems like it would be preferable to our button, now that Wagtail has such a feature.