Different browsers different logo behaviour?

It shows okey there.
I am not a webdev so I can only do diff of html source taken off both browsers and I see this:

-> $ diff brave firefox
1d0
< 

and visually - both for the snapshot & for html source, no user is logged in

Perhaps it’s only that specific release/version I run… or Firefox “digestion & rendering” of the code?
3.0.5 / 461966e028