Keyboard key/charcater runaway (endless repeat) -- nearly giving up -- fix it

Since ~6 Months. I tested everything: new keyboard (same brand), updated drivers, etc. nothing works:

Once every other 10-30 minutes, one of the keys runs away. Completely sporadic, completely random. Any key, space key, or characters. Any software, any app, anywhere. In Windows settings, in Word, in browser, just everywhere.

To get a feeling how it bothers, just watchhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh ... 

At some point I thought about a key-logger, but there is not key-logger in wires and devices that get replaced. Further more, USB-ports were checked, Energy mode removed (please remove it by default), or ports switched. Nothing.

Either, this is down to mainboard, or, my guess, down in Windows 11. All of this is happening only since couple of months, not too long ago. My system is massively powerful and engineered with 30 years Windows/IT experience. No mods, no crap, no bad changes. Just the normal 1 million updates.

If anyone has a tipp, it is highly appreciated. The most annoying Windows issue I have witnessed in last years, only saying the truth.

[Another one is the constant interruption of sound output by either mouse clicks, dragging dropping, or else... whatever has been done here in Windows 11, it was not the case in Windows 10 or early Windows 11.]

Kind Regards