Earphones Bluetooth Volume is too low, tried everything, also tried same earphones with other phone and were OK (volume was even too much), so definitely device/huawei problem. Checked forum and there should be same troubles with Mate 20 model and no solution? What is that, some new sound policy of top huawei models? Really do something about it, its destroying my customer experience with otherwise excellent phone...
Best answer by ClogPower
In developer mode you can check option for 'Bluetooth absolute volume'. See if that helps.
You can also try to use software to adjust volume;
I used this on a different phone, haven't tried on P30 yet.
I hope above tips help