I been a Firefox since around 2010 (desktop) now on Android i even love this despite of heaviness in resources but efficient, there's only reason why i keep not using Firefox on Android, it is the mobile data bandwidth usage, even with strict ETP and pair it with ublock origin (easy mode or medium mode) and localcdn (that should help saves mobile data) but still consume high mobile data. Like just opening a comics style website brave uses obly around 30 probably 50 mb max but in Firefox it already consume around 100-120 mb.