What loading into a previously played local server, the screenshot is displayed as expected while "loading terrain" ... but then in the last few seconds as it says "generating chunks" the screenshot gets zoomed and turns 90 degrees counter-clockwise during that phase. Kinda disorienting.

MC 1.20.1
Fabric 0.14.22
Seamless-Loading-Screen 2.0.1
... tried 2.0.2 but that crashes in console before client starts up.

Would be great if you could get a video of the situation as I have never seen this before. Maybe even a log file of the test too.

In the log, the rotation is seen at about [2:27:53] Line 1840
https://paste.ee/p/AVkku
I have a bunch of mods, I know, but if you suspect one, I'm cool on testing without that one.

And video...

This is caused by a shader in the Stellarity datapack.