All edits to MediaWIki namespaces are timing out on translatewiki.net. From some manual testing it seems that https://gerrit.wikimedia.org/r/#/c/230967/ is the cause, though I do not know why. Reverting to 3a252efa12253e77a07a75da25bcf558c5bcd209 stops the timeouts.
In addition, I am also seeing constant queries for re-loading message cache and this message in the debug log:
[MessageCache] MessageCache::load: Loading en... global cache is expired/volatile, loading from database