Thank you for reporting a bug to Unity.
After reviewing the behavior, we've confirmed it aligns with the current design and intended use of the feature. We understand this may differ from your expectations or workflow.
Verified workarounds (no code changes required):
- Transparent surface type — the bypass define isn't emitted for transparent, so the clip runs live in Forward. Single pass, works immediately (with the usual transparent sorting/blending trade-offs).
- Two custom passes (stay opaque) — a first DrawRenderersCustomPass with Pass Name = DepthOnly (Override Depth on, Write Depth on, ZTest LessEqual), then the Forward pass with Override Depth disabled so it uses the shader's native ZTest Equal. This reproduces the native flow and clips correctly.
We will close this case as 'As Designed.' If you have feedback on how the feature could better meet your needs, please let us know - we value your input and consider it in future improvements.