To clarify, by default anons don't see the red exclamation marks in Special:RecentChanges either.

Gerrit change 148300 . Does this need to be documented in the release notes as a configuration change?

(In reply to Nathan Larson from comment #2)

Gerrit change #148300 . Does this need to be documented in the release notes
as a configuration change?

Yes.

Change 148300 had a related patch set uploaded by leucosticte:
Let anons see what was patrolled

https://gerrit.wikimedia.org/r/148300

See also Historical context around RCPatrol.

The ability to patrol edits was disabled on en.wikipedia.org in 2005 shortly after the feature's introduction due to a dislike for the exclamation marks. While these were, I believe, at the time only visible to sysops or at least could have been limited to a user group separate from that (one that sysops can grant themselves if they wish), the feature was instead disabled entirely. I imagine the sentiment has since changed, but for context at least it may be useful to keep in mind that there is precedent for not liking to "see" these exclaimation marks.

As for transparancy, I think that's what logs. We have patrol logs, which are public at Special:Log/patrol. I don't have an opinion on whether to display the indicator, but it doesn't seem unreasonable to limit this interface to users that can act on the information. There may be also be an angle here in terms of abuse, e.g. we don't make public whether a page is unwatched, I could see an argument for not wanting to make it super easy to browse recent changes on small wikis and looking for unpatrolled edits toward the end of the RC cut-off for possibly unmonitored subjects.

Having said that, the feature is configurable, so individual wikis could always experiment with this once there is local consensus to assess how useful/desirable it would be for all users to see it by default.