[Enhancement] RTC: incompatible-plugins warning should name which plugin (or metabox) is causing the incompatibility #82100

Description

When Real-Time Collaboration is disabled on a post because of an incompatible plugin (Core disables RTC on any post containing certain metaboxes), the warning tells the user that it's blocked but not which plugin or metabox is the cause. Users have no way to identify the offending plugin without disabling their plugins one at a time to find the culprit.

Reporter's own words (August 2026)

Testing on her blog instead with SlimSEO active, I got a warning that collaborative editing was not enabled because of incompatible plugins in the post, although it was not specific about what was incompatible.

Also worth noting (separate observation)

The reporter observed that on a different site the warning was inconsistent between the two users testing together — one user saw the warning, the other didn't. Not sure if that's a separate issue or a symptom of the same detection running per-user rather than per-post

Environment

• WordPress 7.1 / Gutenberg 23.8