Flickering/Pulsing Display on XPS 9570

On a Dell XPS 9570  (Intel Core i7-9750H, 15.6”, 4K UHD, 16GB, 1TB SSD, NVIDIA GeForce GTX 1650 4GB), I have a sort of pulsing behavior with the screen: the brightness varies slightly, but enough to become annoying. It's visible specifically when writing text on white background. The whole screen is affected. It can't be captured on a phone video, as the variations in brightness are too low, but the problem is that when it occurs, it varies rapidly, so the eyes register it quite well.

What I've observed so far:

• Only happens when the AC adapter is connected 
• Doesn't matter if the battery is fully charged or not. As long as the AC adapter is connected, it will eventually show up - it might take a few seconds, or more than 1h
• It might do this occasionally for a couple of minutes, then it goes away for several minutes or more
• Can't link it to low / high usage of the laptop (eg high CPU / high disk usage / etc)
• Changing resolution doesn't help
• I used to be able to "fix" it instantly in the past, by toggling the "Panel Self Refresh" option in Intel's display drivers. However the current version of the Intel Graphics Command Center no longer has a tab for "AC" under System->Power
• Tried installing older drivers, as well as being up-to-date, but the problem still occurs
• Disabled / re-enabled HDR without any change
• Changing the frequency from 60 to 59 and the other way around doesn't fix it
• Changing the graphics adapter used in Nvidia Control Panel has no effect

Any idea on what could I do to identity the cause? Or perhaps someone knows a fix for this problem?