I've upgraded my Unity project from Unity 2020 to 2021 LFS, using the URP pipeline, and I'm now seeing these lighting artifacts in scene view and game view caused by the Universal Render Pipeline/Lit shader. I generated the mesh for the floor using Polybrush. I've turned off lights and destroyed all baked lightmaps, but I still see these shadow looking artifacts. Has anyone experienced this or have tips for fixing this?
Edit
I changed the render pipeline asset from Universal RP-Medium Quality to a render pipeline asset from a third party package, and it seemed to fix the problem. I tried removing Universal RP and redownloading it to verify whether I had messed its settings up, but I kept seeing the same artifacts. I am sure now that the problem lies in this render pipeline asset, but I do not know how to fix it.
Shadow artifacts in the unity editor can occure due to wrong cached light data. If you delete the library folder and reopen your project the lighting data will be regenerated.