If you are seeing an "Update Required" message or playback issues:
: Sideloading apps using tools like AltStore or Sideloadly requires an Apple ID; using an unofficial IPA can sometimes trigger security flags. youtube 15021 ipa download upd
"YouTube 15021 IPA" is almost certainly an unofficial, repackaged IPA that carries security, legal, and privacy risks. Use only official App Store apps; if installed, remove it and follow remediation steps above. If you are seeing an "Update Required" message
Google changes its server-side logic frequently. Even if you get 15.21.1 working today, there is no guarantee it works tomorrow. You might open the app to find an error message saying "Update Required" or "Login Failed." Google changes its server-side logic frequently
An (iOS App Store Package) file is the format used for iPhone and iPad applications. Modified IPAs—often called "tweaked" apps—are popular because they integrate features typically locked behind a YouTube Premium subscription.