DisplayPort not detected on ThinkPad T14 Gen 3 with Ubuntu 22.04

I am having series issues connecting external monitors to my new ThinkPad T14 Gen3. For once it cannot detect the HDMI port at all, which is annoying but avoidable as it can detect HDMI via a dock station connected through USB-C. However, one of the monitors I have only has VGA, DVI and DisplayPort connections, and my dock station only has DisplayPort, so I can only connect it there. But it just won't work. It doesn't even detect there been any DisplayPort at all, here is the output from xrandr -q

Screen 0: minimum 16 x 16, current 1920 x 1200, maximum 32767 x 32767
XWAYLAND0 connected primary 1920x1200+0+0 (normal left inverted right x axis y axis) 300mm x 190mm
   1920x1200     59.96*+
   1600x1200     59.96  
   1440x1080     59.99  
   1400x1050     59.98  
   1280x1024     59.89  
   1280x960      59.94  
   1152x864      59.96  
   1024x768      59.92  
   800x600       59.86  
   640x480       59.38  
   320x240       59.52  
   1680x1050     59.95  
   1440x900      59.89  
   1280x800      59.81  
   720x480       59.71  
   640x400       59.95  
   320x200       58.96  
   1920x1080     59.96  
   1600x900      59.95  
   1368x768      59.88  
   1280x720      59.86  
   1024x576      59.90  
   864x486       59.92  
   720x400       59.55  
   640x350       59.77  

which correspond to the main laptop display, but nothing about any other ports. Is there anything I'm missing or should do to get it to work?

Update: I just did a BIOS update following this post. It resolved the HDMI issue. At least it detects the monitor, which it didn't before. It shows no signal but it's an old monitor connected with a VGA cable through a VGA to HDMI adapter, neither of which is particularly reliable so that might be the reason. I will test with a proper HDMI cable and new monitor as soon as I get one.

Nevertheless the DP issue remains, does not detect the monitor nor it shows up anywhere that the port is available.

I have a definitely not ideal workaround for this that I found for my Laptop.

I have the t14s gen3 but my CPU is the Ryzen 7 PRO 4750U with Radeon Graphics Interestingly it suffers from a very similar displayport as the one linked that is linked in the Original question.

The USB-C Displayport works however, if i use kernel version

5.15.0-43.46-generic

Any recent kernel that's available normally as update after this version breaks it.

So you might be able to solve it by downgrading to that kernel version if you're willing to try. I'm still looking for another Solution though that lets me upgrade my Kernel again...

Another interesting factor is that this doesn't happen with every display. i'm using a Lenovo USB-C Docking monitor at work and this works for some reason.