@ArielGlenn, two fiwiki users reported about this between 03–03:35 (UTC) and one user (who said that only mobile phone interface worked) at 7:49, 27 June 2019 (UTC) .

In T226048#5269073, @Wurgl wrote:

A really bad quality video of refreshing my watchlist. You see the watchlist and at 0:17 - 0:36 you see a slow refresh.
https://www.youtube.com/watch?v=W7r6DvmnfnE

Just to give you an idea about the term "slow".

If you check my deleted contributions, all links to the Wikiuutiset:Hiekkalaatikko (the sandbox page; search for ”25 November 2007”) are red, although the page itself exists. When I searched my deleted edits in the Wikiuutiset namespace (id 4) only, Wikiuutiset:Hiekkalaatikko didn’ t show up at all and the resulting message was: ”No changes were found matching these criteria.” Pathoschild imported revisions into that page from Wikimedia Incubator on 25 November 2007. Apparently the list of my deleted contributions (which I can see with temporary admin rights) still lists the edits that I did on Incubator and were removed before the import, but when I click their revision links, I get this message: ”Invalid or missing revision. You may have a bad link, or the revision may have been restored or removed from the archive.”

The link to the Wikiuutiset:Etusivu (aka the main page) appears as red also in the deletion log if you select ”Page undeletion” from the ”Type of deletion” drop-down list:

fiwiki: Throttle groups are empty for filter 99. Please add some groups or disable throttling, then launch the script again.

Fixed.

Object replacement character appeared here at the start of my edit summary (right before the word ”useinmiten”):
https://fi.wikipedia.org/w/index.php?title=Luettelo_televisiosarjan_Simpsonit_hahmoista&diff=prev&oldid=17693780

In T177661#3666640, @Peachey88 wrote:

arbcom-fi is listed as a private wiki so blocking the account will disable the login

More examples of the same problem from fiwiki:

This phenomenon has been spotted on several fiwiki pages, too. See this, for example:

The goal is to replace the 'oversight' group in production with 'suppress', at which point we could drop 'oversight' from Flow too.

(Note: I moved this comment from Grant 'flow-suppress' to the 'suppress' group as well to this task. My comment relates to the aforementioned change.)