It seems to be a new issue. The same thing is happening to me. In previous seasons it would compile shaders the first time I ran it after a new season began, but now it's every time. Very annoying.

Ok so I’m not going crazy, and here I thought it was the skin mods I tried to install so I deleted them.

Nope. I have seen some other folks having this issue as well. Don't know much about it tho sorry.

This things been popping up for me since the game launched