A brief and (hopefully) final update to this saga. UPS bought the console back yesterday right to my front door (which was nice) - or well, not the console but a console, according to the attached letter I received a new unit. I guess whatever was wrong with the old one was so fundamentally borked it wasn't worth trying to fix it. But seems to work fine now. The whole process took 13 days, which considering the pandemic and that it went to France and back isn't too bad at all. And it didn't cost me anything, other than the hassle of going to the post office. It'd be even nicer if UPS/some other courier would pick up the return from home as well, but I guess you can't have everything. In the end, I have a working PS5 and MM looks completely sweet in the 60fps RT mode. Life is good again.