User A uploads “image.jpg”, user B uploads “image.jpg”; A's upload is replaced by B's upload, both users end up with the same avatar.
I was attempting to achieve this unsuccessfully.
If you want to customize then child theme will be safe option for you. You can customize thorough child theme because it is perfect for overriding and also it would not be lost on updates.
I tried copying the function and modified it in the theme functions, but it doesn't work. Maybe I'm not doing it correctly… ?
I have edited the plugin functions for now as I need this working. The avatar uploads include the attachment ID in the file name and the resize crop was changed with no problem.
There's also a funny thing going on:
The Default Avatar options in the Discussion Settings show my own avatar; but it's just in the layout, selecting each option does work accordingly.