How to reproduce:
1. Open users attached project "Bug.zip"
2. Open "scene" Scene
3. In the Scene View, move the camera around and observe how the spheres behave

Reproducible with: 9.0.0-preview.14, 9.0.0-preview.35 (2020.1.0a23, 2020.1.0b15, 2020.2.0a17)
Not reproducible with: 0.1.21-preview, 4.10.0-preview (2018.4.24f1), 7.3.1, 7.4.1 (2019.4.3f1), 8.1.0 (2020.1.0b15. 2020.1.0a17)

Notes:
Creating a material and setting its Surface Type to Transparent in 8.1.0 or earlier and then upgrading to 9.0.0-preview.14 or later works fine, but if you then switch between Surface Types of the same material in 9.0.0-preview.14 or later, the bug appears again. Not reproducible with HDRP.
Reproducible with URP Lit, Unlit, Simple Lit, Baked Lit, Particles/Lit, Particles/Simple Lit, Particles/Unlit shaders.
In the Shader Inspector window, dragging the Priority slider sometimes fixes the issue and the material is rendered in Transparent pass, but changing the alpha channel value resets the issue.