Hi. I have the same problem as with my previous 5700xt, when set 144 hz in desktop, 6800 XT memory go to 3D MODE :(, monitor issue? AMD issue? Display port cable issue? :S
Monitor issue probably.
The monitor manufacturer has likely used non-VESA standard VBlank timings for the 144Hz mode to save on bandwidth.
This greatly reduces the amount of blanking time the GPU has between each line in a frame and thus forces a higher memory clock to compensate.