IDK, I worked at Google for a long time and the people who cared about browser compatibility by far the most were the Chrome and Workspace teams. The Chrome team tried to emphasis that it made it very hard to negotiate web standards and made them look bad if Google had Chrome-only properties and Workspace wanted browser compatibility because they needed to officially support browsers that their customers were mandated to use (but they didn't really care about the long tail of browsers).

I'm guessing that Mozilla takes browser compatibility even more seriously. And here's an addon to change the user-agent string for Google search so you get the same experience as a Chrome user: https://addons.mozilla.org/en-US/android/addon/google-search.... Off the top of my head, Google Groups content often hangs on my mobile Firefox browser, while Chrome access is always speedy.