Steam Deck drains battery while in sleep

[UebelBAM]

My Steam Deck OLED has a weird sleep behaviour for a few weeks now. Normally, i could put the Steam Deck into sleep, and use it again tomorrow. Battery would drain, but only slightly. That is expected.

Recently however, the battery would drain about 7-8% per hour, while in sleep. And the back is constantly warm. It seems the APU is not going into a low-power state. Functionally it all seems normal. I press the power button, the animation and sound play, display turns off and the Steam Deck becomes unresponsive to button inputs. All seems normal, except the warm backside and heavy battery drain. Basically makes it impossible to quickly use the Steam Deck tomorrow. And i can't put it in the case while in sleep. The heat accumulates and the whole case will be warm. That's how i noticed it in the first place.

I have tried several things, resetting the BIOS, re-image SteamOS or several different update channels. I even tried Bazzite, and had the same behaviour. So might be a bug in the Firmware?! Unfortunately i can't say exactly when this problem started. For now, i have to shut down the Steam Deck completely.