My systems standard language is german, but the surface of Revolut and Spotify uses the english language. In Revolut's preferences the language is shown as "english", when I click on that, I'll be directed to the Android systems language settings, which is correctly set to "standard (german)", back to Revolut, the language stays english, even when I switch directly to german language (and back to standard). Same in Spotify.
Sometimes after an update via Aurora the language in Revolut went back to german, but after the following update back to english again.
Surprisingly in Aurora the date of each upstate in the list is shown with "avr." for this month, but in german it should be "Apr." or "April".
So what might cause the problem, GrapheneOS, the apps themselves, missing firebase stuff or wrong app versions from Aurora?