Edit: I’m glad so many of you have had no issues with multiple monitors. My set up is a little unusual (3rd display is an infrequently used large tv hooked through the receiver) and is definitely solveable but will take some effort (and honestly, I’d rather spend my spare time outside or with friends, so who knows when I’ll fix it.)
This makes it seem like Linux has a problem with multiple monitors when you just aren’t supposed to connect your 80s AV hardware between TV and computer. You should absolutely expect that to either require an active convertor to your obsolete shit AND OR cutting out the intermediary. If you are going to use weird shit its on you to actually understand how it works.
Out of all the people on earth you might literally be singular person anywhere with this setup. Meanwhile everyone else is just plugging in shit and watching it work.