URGENT-SPHERICAL CUTOFF AT POSTPROCESS using WORLD_POSITION

Hello there I made some really good water some eg:


Now I am looking for making a postprocess for underwater with waterline however I noticed all methods using clip plane value involves uses CameraVector , which when used more than FOV 96+ will cause ugly spherical cutoff when traced against vacuums or skyatmosphere.

I tried making custom Camera vector using WorldPosition node but again when I am normalizing it ; it will have the spherical cutoff.

I want to know why it happens? and where I need to do the fix