Recently, on several different occasions I had Assistant switch languages halfway through a conversation. Here is an example that shows conversation starting in English (first question, first answer, and second question), but then the second question is answered in Polish:
My browser reports supported languages as en-US, en, pl, pl-PL (from my experience, websites typically use only the first one and ignore the rest) and I connect from Poland - one of those probably trips Assistant off.
Interestingly, the quality of Polish language used in the reply is extremely poor, up to a point that it contains non-existing words:
"niewalnych" is not a word. (I mean, grammar rules of Polish allow to create such word by combining negation "nie" with an adjective "walny", but even then the grammar of this sentence is completely messed up.)
