Your "WaterSurface" shadergraph is screen-space sampling your _ExcluderDepthNear and _ExcluderDepthFar for all shader passes (opaque, depth, shadow-caster, etc.), which is causing non-camera-aligned passes to discard pixels incorrectly.
In your case, the "ShadowCaster" pass is sampling these camera-aligned textures and discarding shadow-map pixels incorrectly in `_ShadowmapCascadeAtlas` (used to later compute volumetric lighting), leading to its corruption and rendering artifacts (position the camera inside the capsule, open the `FrameDebugger` and observe the contents of your shadowmap at the end of the `RenderShadowMaps` section).
You have two possible workarounds here:
- If you're ok with the clipped-area not affecting the shadows/god-rays, you can add a custom HLSL block to your shadergraph, where you disable this near/far test when `SHADERPASS == SHADERPASS_SHADOWS`.
- If you want to affect the shadows/god-rays, you need near/far textures per-view (each camera, shadow-casting light, etc.) and sample the correct one based on which view you're rendering. This will increase the effect complexity significantly, but it's the only way to represent that volume-cutout correctly for all passes.