Ubuntu 18.04 Dual Monitor setup; the vertical (portrait) monitor only has screen tearing

I'm running Ubuntu 18.04 on a machine with a core i7 CPU, Nvidia GTX 3070, with nvidia v510 drivers. I have two nearly identical 4k monitors (with their respective monitor settings set nearly identical as well). One monitor is in landscape orientation, the second in vertical or portrait orientation. Both are connected through display port.

I observe that only the vertical monitor experiences what I think is minor screen tearing (looks similar to as if it's running at a lower FPS). The effect is minor but clearly noticeable when moving windows or mouse from one monitor to the other.

Here is my output of xrandr

Screen 0: minimum 8 x 8, current 6216 x 4224, maximum 32767 x 32767
HDMI-0 disconnected (normal left inverted right x axis y axis)
DP-0 connected 2376x4224+3840+0 right (normal left inverted right x axis y axis) 600mm x 340mm
   3840x2160     60.00*+  30.00  
   2560x1440     59.95  
   1920x1080     60.00    59.94  
   1600x900      60.00  
   1280x1024     60.02  
   1280x800      59.81  
   1280x720      60.00    59.94  
   1152x864      59.96  
   1024x768      60.00  
   800x600       60.32  
   720x480       59.94  
   640x480       59.94    59.93  
DP-1 disconnected (normal left inverted right x axis y axis)
DP-2 connected primary 3840x2160+0+685 (normal left inverted right x axis y axis) 600mm x 340mm
   3840x2160     60.00*+  30.00  
   1920x1080     60.00    59.94  
   1600x900      60.00  
   1280x1024     60.02  
   1280x800      59.81  
   1280x720      60.00    59.94  
   1152x864      59.96  
   1024x768      60.00  
   800x600       60.32  
   720x480       59.94  
   640x480       59.94    59.93  
DP-3 disconnected (normal left inverted right x axis y axis)
DP-4 disconnected (normal left inverted right x axis y axis)
DP-5 disconnected (normal left inverted right x axis y axis)

Here are two screenshots of the display settings for both monitors:Landscape/main monitor, Vertical Monitor

Stuff I've tried

Following advice in other questions about similar issues, I've tried setting Force Composition Pipeline and Force Full Composition Pipeline in all sorts of combinations for one or both monitors through the nvidia-settings gui for X server Display Configuration, with and without running the tool as sudo, but no combination of options improves the issue.

If I set the vertical monitor to a landscape orientation, it runs smooth as butter, with no screen tearing/low fps observable. So it seems as if the problem only occurs with one monitor being vertical, the other being landscape.

I tried adding options nvidia-drm modeset=1 to /lib/modprobe.d/nvidia-graphics-drivers.conf and running sudo update-initramfs -u and rebooting, but also had no effect. However I've found conflicting info about where/which file should be created/modified, i.e. in/etc/ or in /lib/, and that setting this value sometimes results in boot breaking.

Any advice?