MacBook M2 2022 - Excessive battery drainage when fully shutdown

My MacBook M2 (2022, Sequoia 15.0.1) suffers from severe and excessive battery drain when powered off. The battery discharge rate in off mode is -1%/hour, which means if I turn it off with a 100% battery and turn it on after 4 days, the battery is completely drained.

It seems to be due to software and not hardware because:

• It is not ordinary battery self discharge (discharge battery is excessive). My Mac has not been used very often, and battery health seems to be ok (Battery is 1.5 year old, Max capacity 100%, cycle count=45, health status OK)
• This issue appeared suddenly ~ 2 months ago (~ August 2024), it was not a deteriorating battery performance. Possibly after a iOS update (I do not remember which one).
• While the MacBook is turned on or in sleep mode the battery drainage is OK and in the expected range (which means that in order to save battery I have to put the Mac to sleep rather than shutting it down - absurd!)
• I tried lots of different settings with no result (turned off location service, siri, tried all battery options, uninstalled unnecessary software, etc)
• no device connected to USB ports

Any help? I found same issue posted by other apple users, but with no satisfactory answer or solution (let alone official response/solution from Apple). I apologise in case a solution was found and posted (I may have missed it).

Thanks :)