That seems hard to believe as it would imply that they have code specifically to cripple the Firefox experience. It's probably at worst that they intentionally don't optimize their sites for Firefox and not actively making it worse.
I think it's more the case of enhancing the Chrome experience and not doing anything to deliberately impact firefox.
The sites served to non-Chrome receive less QA resources, as far as I can tell, and are often buggy in various ways. Simply spoofing the Chrome UA in Firefox on Android can often get you a site that works better (in Firefox) than the one served to Firefox by default.