Without any info about your settings, your footage and so on nobody can really tell you much. Start by making sure the comp resolution is actualyl set to "Full". Effects respond to the resolutiojn setting and of course viewing things at half res or lower may not allow to correctly judge the quality.
Hi. All of that is set as you said. This isnt the first time ive had issues. I had issues with my 3d editing where layers became see-through. I have after effects 2020 and I have tried literally everything