The Share button is useless, mostly because it's Mac focused and while I'm on a Mac I'm not otherwise part of Apple's ecosystem. Share via GMail might be useful.

I don't believe it can currently be removed (but I really hope I'm wrong).

Having the same issue. Cleared ALL cookies and restarted browser the other day and it cleared for a few days. Now it's back and extremely annoying.

Cleared photos.google.com cookie and restarted browser still happening.

Chrome and Firefox are usually reserved for the work Google account but I logged in in Firefox and not seeing the problem there.