Weird blur in my fisheye HDRP shader

[wet quest]

I am writing a fisheye camera simulator for my project, and for that I decided to try writing a custom HDRP shader. The actual fisheye effect seems to work but for some reason everything is blurred in one direction or another. This was happening while I developing the shader too. This doesn't seem like a simple fisheye distortion as it doesn't follow any fisheye lines and happens on the entire screen area, but if it is, how do i work around overcome this?
Has anyone seen this effect? What causes this and how to fix it?

all tutorials online i saw before were on BRP/URP :/

a bit about my setup:
i have two cameras, one (CubemapCam) renders a cubemap to a RenderTexture and another (MainCam) displays that cubemap on the screen. there is a global postprocessing volume that runs the fisheye effect which actually calls my shader. the volume is on a PostFX layer and MainCam uses that as the volume mask

also, i just realized that CubemapCam also renders to Display 2 and this is what you can see there, so it seems to confirm that the blur does not come from the fisheye distortion

ping on reply pls

shader

[tribal salmon]

Try disabling motion blur from post processing
Just a guess but it could be that the distortion causes a mismatch with motion vectors, so motion blur would treat the distortion as "motion"