Thank you for reporting a bug to Unity.
We acknowledge the issue in Unity 6 with URP Compatibility mode, however this mode is not in development anymore and mostly here to help you to port your projects to URP Render Graph in Unity 6. All new URP projects use Render Graph by default in Unity 6.
The current issue (blue water layer being white with the Feature ON) doesn't appear in URP Render Graph and after verification, the CopyDepth pass is correctly positioned in the list of render passes with the Renderer Feature enabled.
To enable Render Graph with URP in Unity 6, go to Project Settings > Graphics > URP > Render Graph > Disable Compatibility Mode.
You can find more info on Render Graph in Unity documentation, on Unity forum and even on Youtube.
Thank you again for taking the time to report this issue.