External screen with different refresh rate over DP over USB-C

Hi everyone.

I just tried the newest and greatest Manjaro 21 release (KDE) and wanted to get my setup working.

Unfortunately, I don’t manage to use my external monitor with 144hz. Not even when I disable my internal monitor (60hz). I tried both; X11 and Wayland.

When I enable 144hz, the screen kind of goes black on the right half and starts flickering like crazy; switching back to 60hz fixes these issues.

The thing is: I’m running a 4700u notebook (envy x360) with a USB-C-Dock (HP Dock G5) that pushes the screen-signal (DP) over USB-C. All components use the newest firmware versions.

I also tried the newest stable kernel; without success.
I also tried to enable 144hz using xrandr; without success.

Can anyone tell me, how I get this working properly? It’s important to get 144hz on my main screen as I’m using Moonlight to stream games (144hz) from my Windows machine.

Any help is highly appreciated.