This is a bad UX/UI issue related to the fact that the Universal Renderer Asset is showing options unrelated to the 2D Renderer (this asset is required for both the 3D and 2D renderer).
While some of the shadow options clearly don't make sense in the context of 2D such as Cascade Count. Max Distance does, but it's not supported. Moving out unshared data is something that is being worked on by the URP team.