@Feuerfuchs To be fair the browsers Google arguably has banned have a very small userbase. Qutebrowser, for example, uses a relatively uncommon web engine (QtWebEngine, or an old QtWebKit version with security vulnerabilities).

It's not cool that Google restricts access to their websites to only certain browsers, but it isn't like they're banning Firefox or making it slower (like what they do with YouTube). It's probably the fact that making cross-platform webapps across engines is really hard.