Use cnq3 with r_mode 1.

From my QL config :

seta r_mode -1
seta r_displayrefresh 144
seta r_customwidth 1920
seta r_customheight 1080

That is all commands that I have needed to play at 1080 and never seen such problems.

This leads me to believe your problem may result from use of r_fullscreen and r_customaspect that I do not think are needed. For example 1920 by 1080 is setting the aspect of 16:9 already, so I dont see what other r_customaspect command is being used for

Unless Q3 is different than QL then disregard.

Edit: Also your screenshot is only the menu screen, are you sure its also a problem in game and not just on the menu? because I am not sure the menu screen can be scaled, but the ingame most definately can.

change dpi scaling in windows

that was the problem, what kind of stupid i am lol

It looks like you have enabled dpi scaling, so either disable it or use this client

thanks, that's exactly the problem, now it's fixed

Use CNQ3 or Q3E