Does anyone know if the linux-can't-handle-multiple-displays-when-one-of-them-is-4k-and-the-others-aren't issue has been resolved, either formally or informally? I've heard this from several folks, (and seen it firsthand once) and it's keeping me from upgrading my linux laptop for now (I don't have 4k monitors as a part of my work setup).
On Wayland it's generally a solved problem (at work I use Sway, with my internal panel - 13" 1080p, at 1.25x scale, and my external panel - 34" 3440x1440 - at 1x). Especially with Firefox nightlies bringing native Wayland support, it's only going to get better from here, but it's already pretty good.
In Xorg, it's as bad as it ever was, mostly for tech debt / protocol reasons. It can be alleviated somewhat with xrandr hacks, but they're gnarly.
Running latest Ubuntu on a 4k and a 1280x1920 screen. Not ideal, but I can work with it. Some apps still have issues, either to large on the small screen, or to small on the big one... I feel like they're 1 or 2 version away from it being good.
Fractional scaling (125%) is not available. There is a workaround, but I couldn't get it to work.
I had plenty of issues with going back and forth. Finally I just got a Dell 4k monitor. I think it was 700 at the time but I am pretty sure they are closer to 350 now or less. That solved docking and so many other issues like restarting applications, etc.
