I use DSR so that my gaming PC can output a 4K 144Hz signal to my main display and then clone that display to a downscaled 1440p 144Hz HDMI output to send to my streaming PC. This works fine for every other game I play. Apex doesn't allow me to set a 4K resolution to my screen though simply because I have FSR enabled. The borderless game window is 2/3 the size of my screen, and if I try to run full screen, it lowers my screen's resolution and makes it difficult to switch it back to 4K.
I'm uninstalling this game until I hear of this being fixed.
