Quick answer: Unity URP build skybox rendering pink because the Procedural Skybox shader was stripped? Add to the Always Included Shaders list or use a custom skybox material.

Editor renders the procedural skybox correctly. Player build: solid pink everywhere the sky should be.

Add to Always Included

Project Settings > Graphics > Always Included Shaders. Add Skybox/Procedural explicitly. Stripping removes shaders the dependency walker doesn't see.

Or assign a SkyboxMaterial

Pre-bake a skybox material asset. Reference from the Lighting tab; the cooker follows the hard reference.

Verify in the build report

Build report > Shader stripping. Lists stripped shader variants. Look for the skybox; presence in the list confirms the bug.

“Shader stripping is reachability-based. Runtime-only references don't count.”

Maintain a project-level 'always included' shader list. Document each entry's reason; future cleanup is informed.