whystrainwhy
I have similar problems with ARC A770 on my motherboard, which is based on the Z390 chipset. In Windows 10/11, I often see artifacts and flickering.
An example of flickering and artifacts on the screen: https://dropmefiles.com/qIZKZ.
But the cause of my problem might be different from yours. My motherboard's BIOS (2019) didn’t support Intel Arc, so to solve the issue, I had to update to the latest BIOS version. This completely eliminated the artifacts and flickering. But the most interesting thing is that this is the proof that the motherboard's BIOS can affect the display, even when it comes to a discrete graphics card.
For my eyes, the most comfortable image when using Windows and ARC A770 was achieved with Windows 10 22H2 19045.5371, Intel(R) UHD Graphics driver v.32.0.101.6129.
Although I am currently working more with Intel UHD 48EUs (i5-12450h), as it seems slightly more comfortable to me than the Intel ARC A770.