minimal examples: https://test.wikipedia.org/wiki/Topic:Xbm9rkr52tr84rpj, https://www.mediawiki.org/wiki/Topic:Xblss3eypj6i1ih7
The messages "This topic was hidden by 1234qwer1234qwer4" and "This topic was deleted by Clump" show the username as plain text with no links (despite even having a plainlinks class). This is quite inconvenient and does not reflect the behaviour in comments, which link the usernames and add additional "(talk contribs block)" links when hovering over them.
Edit: Same goes for "Summary by 1234qwer1234qwer4" message in the first example.