Steps to reproduce:

1. Open the linked project (or set up a project for HDRP usage from https://github.com/Unity-Technologies/ScriptableRenderPipeline)
2. Switch to iOS
3. Open 'ShadowsTest' scene
4. Focus the scene or game view in a way that the trees would be visible together with skybox
5. Notice the artefacts appearing all over the skybox (see screenshots)

Notes:
Only happens in Editor when target is switched to iOS, doesn't happen on device.
Artefacts only visible when trees are in the field of view together with the skybox.