Because the official app is no longer updated, many "YouTube Go Mods" found online are modified versions of the final official release (v3.25.54). These mods often claim to unlock "Premium" features like: YouTube Go Will 'Go' Away In August - Android Headlines

with nearby friends via Bluetooth without using any data.

directly to their phone or SD card for offline viewing.

Google officially , citing improvements to the main app that make it more efficient on low-end hardware. The Reality of "YouTube Go Mods"