I have done the update to Android 10, as well as the subsequent update that showed up few days after.
The problem is actually worse now. Meaning calling 2 times in a raw doesn’t help. I got to restart the phone for the sound + microphone to be functional again.
I have also been reporting those problems to fairphone, and they sometimes answer. They asked me to do :
*#*#66#*#*as you dial a phone number: the Service Menu will appear.
- Select Service tests > Test Single .
- Press Receiver . The receiver (a.k.a. ear speaker) is used to hear the other person during phone calls. The test will play a pre-recorded track through the receiver. If you cannot hear it, that means it is not working correctly.
Which always worked.
They then asked me to update to Android 10, which made is worse.
If you got that problem, you got to complain to fairphone here :