Bluetooth headset too loud and calendar and timer alarms far too low when calling

• /e/ version: 0.14-q, 0.15-q
• Device model(s): FP3

Summary

When calling with a Bluetooth headset the volume is too loud, calendar and timer alarms are far too low.

The problem

When I call with a BT headset the lowest volume is still a bit too loud.

When playing music the volume control is ok.

Technical informations

Headset: Plantronics, Model EOTE 14

The volume for calls with this headset is ok on my old phone Samsung Galaxy S5 Plus (SM-G901F), LineageOS for microG 16 (Android 9).

Toggling absolute volume control for BT in developer options makes no difference.