@Jakob_WMDE @Pablo-WMDE is that something that we changed recently?

Lemma language was indeed recently touched in T194771 to add the 'mis' language code - but even before that it used to show the names of the languages in the language itself (comparably to the preferences page).

i don't know when it was changed but I'm sure there was state when language names were in preffered language of interface, becuase thanks to language names I learned from this suggester what language code use. Regardless of it I think it's more useful to display them in language of user.

Took another look. There is a case we did not consider in our development setups...

Change 447043 had a related patch set uploaded (by Pablo Grass (WMDE); owner: Pablo Grass (WMDE)):
[mediawiki/extensions/WikibaseLexeme@master] NewLexeme: picking lemma language in user language

https://gerrit.wikimedia.org/r/447043

Change 447045 had a related patch set uploaded (by Pablo Grass (WMDE); owner: Pablo Grass (WMDE)):
[mediawiki/extensions/WikibaseLexeme@master] LexemeLanguageNameLookup: consistently yield string

https://gerrit.wikimedia.org/r/447045

Change 447043 merged by jenkins-bot:
[mediawiki/extensions/WikibaseLexeme@master] NewLexeme: picking lemma language in user language

https://gerrit.wikimedia.org/r/447043

Change 447045 merged by jenkins-bot:
[mediawiki/extensions/WikibaseLexeme@master] LexemeLanguageNameLookup: consistently yield string

https://gerrit.wikimedia.org/r/447045

@Lydia_Pintscher So effectively ever since deploying T194771 we deprived users of translated language names on systems with CLDR installed (e.g. production). This could have been detected by user testing on beta.

We added CLDR to our dev setups to avoid this happening again.