[Gelöst] Category name singular and plural do not match slug in default language

Background of the issue:
I am trying to set the Category taxonomy name in Polish, but it appears in English in both singular and plural forms. The original language is Polish. I have attempted to change the language to Polish for the Category taxonomy, but it remains in English. See screenshot 1 and screenshot 2 for reference.

Symptoms:
The Category taxonomy name is in English instead of Polish, and the slug does not match the language. After changing the language to Polish, it still appears in English.

Questions:
Why is the Category taxonomy name appearing in English instead of Polish?
Why does the slug not match the language?
Why does the Category taxonomy name remain in English after changing the language to Polish?