Strange. I'm not seeing any issues with Linux and 4k. I'm running a plain Debian 10 with OpenBox running on 4x 4k (3x 28" in a row and one 11" 4k under the right-most) monitors though, granted, I only normally have one web browser that follows me around, across work spaces pinned to the right monitor, mostly maximized Sublime on the middle monitor and a pile pile of alacritty/xterm windows on the left-most monitor. The small monitor which content also follows me around contains clipboard, clocks, Slack and monitoring.
What is the software that people are using that creates problems?
