Same, solid black on my PC, rocking the default wallpaper on my phone. Interestingly, when I switched to using graphineOS, the default background is solid black, so I have that on my phone now as well, too. I prefer it for the less visual distraction, and the fact that on pled screens it saves battery
I’ve always had to manually add my GPU to system monitor, and since I’ve always had integrated GPU as well, had to sort out which GPU is the dedicated GPU before knowing what service is using which GPU. But this definitely is my favorite method once I get it all set up, makes it really clear if a steam game is using the wrong GPU