RTC: block list flickers on the observer side when a collaborator edits a long List block #82098

Description

With RTC enabled and two collaborators editing the same post, when one collaborator edits a long List block the other observer sees the block list flickering on their side.

Not observed with small lists in follow-up testing — appears to only surface with longer / heavier list content.

Reporter's own words

While 1 editor edits a list, the other sees the blocks list flickering.

Environment

• WordPress 7.1 / Gutenberg 23.8 (RTC enabled)