dynamic resolution postprocessing / blit rules?

I'm using dynamic resolution in a project but its not playing nicely with blitting. When using
OnRenderImage(which I would prefer to keep using) it seems like the RenderTextures are already back at full resolution instead of the reduced one, as I'd expect.
When injecting my postprocessing as a Commandbuffer I can Blit at the reduced resolution, but the sample points don't line up with the pixel centers anymore which causes problems in my case as I put special data into rendertextures that shouldnt get interpolated.

Is there documentation on all of this anywhere (I couldn't find any thats indepth enough to give me answers), have you worked with this before and can give me a few pointers? Thanks a lot for your help in any case!