Since my previous message seems to have been removed by the forum moderators, I won’t dwell on that.
I would, however, like to confirm in this new post that the problem is 100% related to call recording.
@GrapheneOS I made a call from my grapheneos device to another phone of mine, started recording, and after about 10 minutes the audio server crash appeared.
Then I made a second call, this time without recording, and left it ongoing for an hour and a half. There was no problem at all.
I hope you can identify a workaround for the upstream bug that is triggered when call recording is enabled.