Problem when magsafe is connected

I have a macbook pro M1 2021. It is always connected to power with the magsafe. The battery was always on 80% as it should be. Since one week it charges to 100% what I didn't ask for. But the worse is that from the moment it is at 100% every one to two minutes the light on the magsafe goes out for a second and a peep is heart when the light is on again. I've tried the poweradapter and magsafe from my wife but it acts the same.

I drained the battery until the computer stopt working but that no effect, Does anyone have a solution for this?

Thank you.