The ‘pink shader’ problem has several causes.
In my case I am using a custom shader package which was fine then for no apparent reason all of my custom shaders appear pink in my Scene view.
I’ve tried
-reimporting the shader package to my project.
-emptying my GI cache
-checking for any missing materials or shaders in my materials
If I create a brand new empty project and re import this custom shader package, everything is fine!
Which leads me to think this is somehow Project Settings related.
What would be some good troubleshooting steps to try next?