Google continues to support the legacy backend for Lollipop devices until at least late 2026. That means older YouTube app versions (17.xx and 16.xx) can still stream videos, log into your account, and access subscriptions—but without new features like “Shorts” algorithm improvements or enhanced live chat.

Do not search for "YouTube" in Google, as it may try to force-open the broken app. Type the URL directly into the address bar. Create a shortcut on your home screen for quick access. 2. NewPipe (Best App Alternative)

Official support for Android 5.1.1 has effectively ended. While you may still have the app on your device, you are likely encountering "Update Required" prompts or "Server 400" errors.

Version 5.1.1 debuted the "Card UI." Videos were presented as white rectangles with thumbnails, titles, and channel names, set against a gray background. This replaced the older list-view style and introduced the ability to swipe videos away from the "Watch Later" queue—a major UX innovation at the time.