Installing YouTube on iOS 12.5.7 is tricky because the App Store officially requires iOS 15.0 or later
"This app is not compatible with this version of iOS, but you can download the last compatible version" Apple Support Community install youtube ios 1257 best
Web Browser Alternative: If the app is unavailable or unstable, use a mobile browser like Safari or Brave to access m.youtube.com. You can "Add to Home Screen" to create a shortcut icon for quick access. Installing YouTube on iOS 12
This creates an icon that functions almost exactly like the app but bypasses version checks. 2. The Jailbreak Tweak (Advanced) install youtube ios 1257 best