Strange keyboard malfunction

I'm happy with ZOS (16.3 Core) on my Dell E7240.
Works like a charm. But...

When typing keyboard randomly tends to infinitely multiply the last character or function I pressed.

For the context:

  • it happens every few minutes on Chrom as well as on Firefox
  • same time I use wireless mouse (via USB WiFi dongle) - which works fine and built-in touchpad - also works OK