Image Effect causes anti alising

Hello, I have a weird problem where screen gets anti-aliased when using pixelisation image effect. I've tried many different pixelisation assets but it happens all the time.

I'm assuming it happens during OnRenderImage() method of the pixelisation effects as RenderTexture is internally created when using the method.

When I manually create a RenderTexture and assign it to camera's TargetTexture to render my screen with the pixelisation effect, the above symptom doesn't happen.( But when checking "Allow HDR" option on the camera, the screen gets anti-aliased again)





Above image is the AAed screen(when using pixelisation effect). It should be all white and red but it looks like the shader is sampling AAed colors. It's very noticeable since....screen get pixelated.

I thought it has something to do with HDR rendring automatically forced within OnRenderImage method but using [ImageEffectTransformsToLDR] attribute didn't work.

Does anyone know what's happening and how to completely disable AA/MSAA/HDR or whatever causing the AA effect?