Thanks! Yes, indeed I found it in developer options, but it does not work. When I choose LHDC the bluetooth codec stay with AAC.
With my Huawei device it´s shown HWA and the sound seems to be better.
Mi9SE I did not had problems with the update. I'm using Twrp 3.3.1-1018 from LR Team.
Try switch off. Press long time power off.
Start Recovery with I guess volume down power on. Make a clean install.
Check MD5 first.
It´s working fine. Lower brightness than 9.10.31 and variabel with ambient light.
As well notification light works (but only one time with incomming message)
During download time notification light is allways lighting.