The problem is largely X11. Wayland desktops such as GNOME + Wayland applications generally work very well with HiDPI.
Even X11 applications work reasonably well on XWayland on e.g. GNOME, as long as all screens use 100% or 200% scaling. Unfortunately, with fractional scaling things break down with X11 applications.
Even X11 applications work reasonably well on XWayland on e.g. GNOME, as long as all screens use 100% or 200% scaling. Unfortunately, with fractional scaling things break down with X11 applications.