Some shaders seem to have artifacts when Easel is around. It appears as a long shadows from the easel. I believe it could be an issue with normals.

Don't have access to testing environment, but I think it was two of Complementart, Sildurs or VanillaDefault shaders

The observed effect is called Shadow Acne on the canvas, but the shadows on the ground were weird too, I might've messed up with normals