Unity Boat Race URP Underwater Surface Flip & Reflections

PlanarReflections.cs

// find line
Vector3 normal = Vector3.up;

// replace with
Vector3 normal = realCamera.transform.position.y < 0 ? -Vector3.up : Vector3.up;

Water.cs

// find line
var matrix = Matrix4x4.TRS(newPos + transform.position, Quaternion.identity, transform.localScale); // transform.localToWorldMatrix;

// replace with
var matrix = Matrix4x4.TRS(newPos + transform.position, Quaternion.Euler(0, 0, cam.transform.position.y < 0 ? 180 : 0), transform.localScale);