Hi, I'm running this mod on LoliServer service core 1.16.5, and the screen like the picture keeps appearing in the background

It does not seem to affect the game, but constantly brushes the screen
（PS: This paragraph uses a translator, there may be problems with the expression, please forgive me）

I had this same issue too, I was able to fix it by installing serene seaon fix! This is a bug serene seasons caused me when I had MCMT installed on my server.
https://www.curseforge.com/minecraft/mc-mods/serene-seasons-fix/files/3973467