Affects versions 1.8.9, 1.17, 1.18.1 and as I assume, all. There is a weird color glitch with the sky (custom skies are off) where the sky sometimes turns black or green randomly and switches back and forth a lot of times. I've gotten the colors green and black. It sometimes flashes between the normal colors and the glitch colors.
The video is filmed on Lunar Client but it is the exact same on the default Minecraft launcher.
Link: https://www.youtube.com/watch?v=h6kHzu9_m3k&ab_channel=InfinityDK