I think the first thing I would try would be to just render it out with really low quality compression settings, like set the quality to 1 and just make it as bad as you can. That would probably add more realistic blockiness and color distortion. You could even import the rendered video and render it out again with bad compression to further degrade it.
If you want to try to recreate it with effects you could try the mosaic effect, colorama and maybe minimax and just mess around with the settings until you get something you like. To break up the mosaic effect so it only appears in places you can duplicate your video layer, set the bottom copy’s track matte to “luma matte” and then apply mosaic to the top copy.
There are also some presets and plug-ins out there that create a “TV Noise” or “Bad Video” effect, just search google and you’ll probably find something useful.
HTH