Huge battery drain v2.66 firmware investigation

I notice my Venu 2 SQ Music (v2.66) started to have huge battery drain about week ago. Usually it has 5-10% battery decrease per night, but now it's 50%.

Gladly my girfriend has Venu 2 SQ Music as well but she does not update the firmware (her watch has v2.53).

I set all settings on both watch to equal and installed the same version (v5.5) of Garmin Connect app.

Results:

Firmware Battery drain per night Connect app Auto Lock SpO2 Android
v2.53 9% v5.5 Disabled On demand v9.0
v2.66 54% v5.5 Disabled On demand v14.0

I continue the investigation, next time will check with Auto Lock function enabled and equal Android versions.

VENU 2 SQ Music firmware v2.66 vs v2.53