Unable to control call volume on xz2c since update to T (from 1.15 S to 1.15 T)

• /e/ version: currently 1.17T
• Device model(s): Sony Xperia XZ2 Compact (xz2c)
• Developer mode enabled: no
• Device rooted: no
• Trackers blocker enabled: yes

Summary

Since updating to a T build (specifically from 1.15 S to 1.15 T), I'm unable to control the call volume. Regardless of the indicated volume on the relevant widget, volume is "stuck", seemingly on the maximum setting.

The problem

Steps to reproduce

Make or receive a call.

What is the current behavior?

Call volume is stuck at the maximum volume regardless of setting.

What is the expected correct behavior?

Call volume should correspond to the set volume.

Technical informations

Relevant logs (adb logcat)

Please let me know what exactly I should look for in the log.

Relevant screenshots

With the call volume set as indicated below, speaker volume during calls is nevertheless at maximum volume.

Solutions

Workaround

There is no workaround other than holding the phone away from one's ear and moving away from potential eavesdroppers.

Possible fixes

No idea.