Why does QA test only Chrome? Well if there is only enough QA time to test one browser, imagine having to be the guy to explain to the higher ups why it wasn't chrome.
Though I just searched and it seems Firefox has a shockingly low market share in mobile: https://en.wikipedia.org/wiki/Usage_share_of_web_browsers
Perhaps that's why it's not given the attention it needs, how unfortunate.
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Is this just begging for karma? There isn't even version or OS info. How is anyone going to actually discuss this other than just arguing blindly?
It was just something that I noticed when I switched from mobile Chrome to Firefox. You don't have to discuss this blindly, just pull your phone and test for yourself, it'll only take you 2 seconds.
My phone has Android 8.0, Firefox Mobile 68.0