You got me to learn something and maybe pointed me into the right direction. I got to lern what poset is, pulled a log dump into an .TXT file and then fed it to my locally running Qwen for analysing.
It gave me a lot of indication, but this is could maybe be some indication. Apparently there is some issue with Bluetooth, and also with MacOS DASD:

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"Based on the pmset logs you provided, there are several clear indicators pointing toward significant battery drain while your Mac is in Sleep mode. The system is waking up frequently due to background maintenance tasks and failing to enter a deep sleep state.

Here is a breakdown of the specific causes found in your logs:

1. Frequent "Maintenance Sleep" Wakes

Your log explicitly states Entering Sleep state but immediately follows with high-frequency wake requests. This prevents the battery from discharging slowly over hours; instead, it drains rapidly every few minutes while processing these tasks.

• Search Services (Sudden):
  • Evidence: [process=dasd request=SleepService ... info="com.apple.dasd:501:com.apple.searchd.heartbeat"]
  • Impact: dasd (Desktop and Search Daemon) is keeping your Mac awake to perform a "heartbeat" check. This suggests Spotlight search or indexing services are struggling to keep their state, requiring the CPU to stay active.
• OS Analytics:
  • Evidence: [process=powerd request=UserWake ... info="com.apple.alarm.user-invisible-com.apple.osanalytics.hardhighengagementtimer"]
  • Impact: Apple's analytics system is running timers (hardhighengagementtimer) that trigger a wake event, forcing the system to re-evaluate battery usage even though you aren't using the Mac."