If this turned out to be true, is there an antitrust case there?
I experience the same issue and it's frustrating. Not that I use a lot of Google services, but when I do... yeah the effect is noticeable. So much as I like to point a finger, I expect it's just due to them not putting in as much time to make their stuff run perfect in anything other than Chrome.
Example: Google search with firefox mobile has unclickable links if I change my user agent to IE8. Literally nothing happens when I tap a link. They are in too deep and starting to break things.