tomscharbach I have not encountered the issue on my Solus Plasma laptop, but I seldom use Steam on the laptop because Steam overwhelms the setup (8th Gen i5, 16GB RAM)
Steam should not overwhelm that setup by any means. That sounds like a bug too. My 3rd gen i5 and 8 GB RAM have no issues running Steam at all.
@Synaptic Are you also using Solus Plasma? Maybe it's an issue with our Plasma desktop and Steam then, but I find it unlikely.
Anyway, you could try updating to the Steam Beta, or look up some general Steam troubleshooting tips, and see if that improves things.