Far Cry 6 - Dani finally started singing again. :)
I could not find the reason why, but Dani stopped singing along with the radio. On the FC6 reddit it was a hot topic and a lot of players were affected. PC and consoles the like. But the devs said they have not encountered the problem yet. I tried reinstalling, starting a new save from the beginning, nothing worked. But then suddenly! Singing! She (and he) didn't for more than 5 months and I really missed it that time.