volume control not working in voice calls

• /e/ version: 1.3-20220823212872
• Device model(s): Teracube 2e
• Device rooted: no

Summary

While in a voice call, the sound level of the other's voice is stuck to a loud level and cannot be changed.

When the physical buttons are used, the slider on the touch-screen moves accordingly, but the sound doesn't; same result using directly the slider on the touch-screen.

The bug war already there when I bought the device, in may 2022, with /e/ version 1.0; earlier versions of /e/ o.s. didn't fix it.

The problem

Steps to reproduce

Voice-call a phone number or receive a voice call, then

• try to increase or decrease the volume with the slider on the touch-screen and see no effect on the other's voice;
• try to increase or decrease the volume with the physical buttons, see the slider moving accordingly without any effect on the other's voice.