Using a legacy browser on a decade-old OS comes with significant trade-offs:
Users attempting to download Firefox from the Google Play Store on an Android 4.2.2 device will likely find it incompatible. Mozilla officially ended support for older Android versions several years ago. Therefore, the user cannot simply install the latest "Firefox" or "Firefox Focus" apps. Instead, they must turn to specific legacy versions, specifically the "Firefox for Android Beta" builds that were compatible with older architectures, or the specific final release that supported API level 16 (Android 4.1/4.2). Firefox Apk Android 4.2.2
: Older versions lack modern optimizations and may feel slow on dated hardware. Security Risks Using a legacy browser on a decade-old OS