Ok I just did a lot more testing, changed drivers back to the last official beta ones, restarted a few times, and the banding seems to be gone from every glide app except Unreal Tournament 99. At this point I think it appears to be some software issue with the glide implementation in Unreal Tournament 99, as I can no longer reproduce any issues in any other glide application. Not sure why UT99 has this issue, but I can switch to the D3D driver for UT99 if I have to.
Maybe UT99 has an older implementation of Glide that I'm running into? idk.
Maybe UT99 has an older implementation of Glide that I'm running into? idk.