I'd prefer subpages be included as well. If someone edits one of my user subpages, whether intentionally (spam, harassment, etc.) or accidentally (such as leaving a talk page message in the wrong place), I'd like to know about it so I can clean things up (remove the spam or move the message to my talk page).

Per @akosiaris ' last comment, I've taken the liberty to update the task description to reflect the now non-tentative date.

As I said in that discussion, I would give my strongest possible support to this feature for reasons I already listed in that discussion.

The way the diff viewer currently works, it can make it difficult to spot vandalism sometimes with this problem. I hope it does get fixed someday soon.

In T152242#2843046, @native-api wrote:

In T152242#2843038, @Gestrid wrote:

That's probably at least part of the reason the original email system included the disclaimer.

It did? Why was it removed then?

It also keeps the WMF out of possible legal trouble if, say, someone finds out a user's email address using this and starts harassing that user. It's basically a disclaimer warning the user replying, so the user can't then say they didn't know their email would be disclosed. That's probably at least part of the reason the original email system included the disclaimer.

Ok, thanks for the clarification. I just found out about this and the other three Phabricator tasks after someone added a {{tracked}} template to the closed RfC today.

Cenarium, you said to use Special:ProblemChanges. My understanding of the enwiki RfC was that the edits would be listed at Special:PendingChanges. Was saying Special:ProblemChanges a typo?

In T2470#2700439, @MZMcBride wrote:

The harassment arguments seem very weak to me. We already have Special:Contributions with accompanying RSS and IRC feeds. Plus, y'know, browser bookmarks are still a thing. A motivated person can always follow a user in order to harass them, just as we allow a motivated person to follow a user to revert their vandalism. Punishing the helpful and useful users who want this tool to follow and contribute to Wikimedia wikis seems misguided.

Here's a suggestion to limit harassment: Make it so that only trusted users (users with the user flag) could use this feature, sort of like some of the flags given to trusted users on English Wikipedia. We on English Wikipedia have a flag just for using Rollback. I don't see why we couldn't have a flag just for watchlisting users.

Having a way to watchlist user contributions would be useful to keep an eye on potential vandals.

In T141687#2508997, @Perhelion wrote:

I'm not sure it is related but on Commons are also some cache problems (since 2 days) reported (unrelated logged in or not).

Also, I was talking to someone in IRC (specifically the wikipedia-en channel), and they seemed to remember something similar from a couple of years ago. Specifically, they said:

In T141687#2508947, @BBlack wrote:

There haven't been any related changes recently on the cache side of things (e.g. changes in relevant VCL or how purging works, etc). More likely it's a change on the other side of the purge queue (related to... jobqueue? eventbus?). Do we have an idea when the problem started up, to correlate against changes?

Several reports have come in at the English Wikipedia's Teahouse regarding this issue. Perhaps some of their questions there can help narrow down the cause.