I came across an interesting thing: https://github.com/skawamoto0/ditherig/blob/master/ditherig/database.csv. As I understand it, this is for integrated graphics cards from Intel and AMD. We can play with addresses to disable dithering. This can be done in Linux using the devmem2 program, which can be downloaded from https://github.com/VCTLabs/devmem2. It can be built by running make in the directory with the source code.
The app can be run like this (you need to substitute the addresses of your own chip, presumably where it says "Disabled"):
./devmem2 0x70030 w 0x00000000
As I understand, the address can be taken from the 8th column, the size is 4 bytes. For simplicity, you can try filling it with zeros (although, of course, one should properly apply a mask from the 10th column).
I wonder if this will work.
UPD. In reality, as usual, it turned out to be more complicated: in the 8th column, it's not the actual address but an offset relative to it. The actual address is calculated based on the values of Bar1/Bar2.