@taus there are some new threads here on Fairphone 5 issues with some apps, in one case it was “solved” by reinstalling FairphoneOS “not the newest version” then reinstalling iodéOS: Fairphone 5 – problem with calls – no sound / no microphone - #7 by chef
I am not suggesting you take this drastic step, just noting there are others with the FP5 experiencing “weird” microphone issues.