[MacBook Air M1] MacBook battery is draining quickly (+ strange behavior)

For a long time, I used my MacBook with an external monitor, but recently, I noticed that the battery life has significantly decreased.

Here’s the battery status:

Charge cycles: 183

Battery health: 90%

Discharge rate per hour (idle, without load): approximately 6-10%

My investigations revealed the following:

1. After resetting the SMC (by turning off the MacBook with the power cable connected), the issue is temporarily resolved for about an hour. However, it returns afterward.
2. If I completely erase macOS and install the latest version, the problem is again resolved for an hour, but then returns.

I’ve run "Apple Diagnostics", but no issues were found.

Does anyone have any ideas about what might be causing this problem and how to fix it?

If you need more information please let me know.