The preview of files with After Effect files (.aep) does not look like it should be. It has been like this for a long time. I deleted Creative Cloud and installed it again, but there was no change.
I'm guessing that you're running After Effects under Big Sur on an Apple Silicon M1 Mac? The icons should get restored when there's a Universal version of AE (that is to say when you're no longer running the Intel version). As far as I am aware, we have no official date on that yet.
Next time you add an image to a forum post, use "Insert Image" rather than "Insert/edit link" so that your image shows in the message thread without needing to be downloaded.