I seem to be having an issue with the rpi4 to be stuck at same resolution 597x448 4:3.
I have searched google and this forum with sope very usefull solution for this issue but at this point not everything is working.
so i got rpi 4 4GB
os: ubuntu 20.04 headless -> installed gnome-desktop
first issue was having no ui at all so i configured hdmi in usercfg.txt file at /boot/firmware -> working now
for the resolution i have set my hdmi_mode and group and i also found you have a seperate flag for 4k with rpi which is also set.
resolution is still the same.
hdmi is in the gdmi 0 port my tv is 4k resolution so i guess i'll can set the output to 4k aswell
full config now: