See title. More elaborate:

When I view this site on a 4K screen with 200% desktop scaling (Browser scaling 100%.), the avatars are upscaled and look ugly. That's not necessary. A website can adapt to this by showing a higher resolution variant.

I know, it's minor, functionality first, bandwidth etc., but it's something to consider.
Priority 1 in your life should be to find out what priority 2 is.