I've gone for a fresh reinstall of Steam (as that stopped working, too) and RDR2, so hopefully this time I get it right. I'm also using ChatGPT but the results are mixed. It can either be very good and helps out a lot, or it can be a total failure. It's definitely worth the effort though, and the overall impression is very good with using it.
I was certain I was replying directly to the posts above, oh well. "Not Wayland..." at Storm, "I've gone for a fresh...", at StarTreker, and "Do you mean...", at wesoliv429.
And thank you all for your help, by the way. Much appreciated.