I've tried a temporary fix, separating u from x by tagging the former with <nowiki>.

I can't reproduce - I was able to do https://commons.wikimedia.org/w/index.php?title=File:John_Bruton,_February_2002.jpg&diff=prev&oldid=853705020 and it seems to render correctly.

In T357941#9556468, @Pppery wrote:

I can't reproduce - I was able to do https://commons.wikimedia.org/w/index.php?title=File:John_Bruton,_February_2002.jpg&diff=prev&oldid=853705020 and it seems to render correctly.

If you go into the editing interface and, without editing, click Show Changes, it instead changes ux to uxx.

Still no repro.

In T357941#9556475, @Pppery wrote:

Still no repro.

I'm using Google Chrome and another x is added without me editing the interface.

I've tested using Safari on an iPad as well, and I'm having the same issue.

You probably enabled some input method in UniversalLanguageSelector.

In T357941#9556743, @Bugreporter wrote:

You probably enabled some input method in UniversalLanguageSelector.

Yeah, this sounds like the Esperanto X-system to me. See https://www.mediawiki.org/wiki/Help:Extension:UniversalLanguageSelector/Input_methods for details on input methods, and try Ctrl+M for disabling it.

In T357941#9558193, @Lucas_Werkmeister_WMDE wrote:

In T357941#9556743, @Bugreporter wrote:

You probably enabled some input method in UniversalLanguageSelector.

Yeah, this sounds like the Esperanto X-system to me. See https://www.mediawiki.org/wiki/Help:Extension:UniversalLanguageSelector/Input_methods for details on input methods, and try Ctrl+M for disabling it.

Thanks, this worked.