This happens on meta as well and could also happen on other discourse sites, but essentially if I try to upload a square avatar it won’t display it and default back to the letter. However, if I upload a non-square avatar it will display that (after saying that it needs to be cropped).
This also happened to various users, so it isn’t just me.
I ruled out browser extensions and amazon already, so now I’m not quite sure what the issue could be.
I was going to include a gfy/vid but it kept bugging up so I scrapped that idea