Only download IPAs from trusted legacy communities (r/LegacyJailbreak sidebar, MTMDev, or InvoxiPlayGames’ GitHub). Never use "IPA signing services" for bank accounts.
Downloading a standard, unmodified YouTube IPA from 2016 will not work immediately.
This tricks YouTube's servers into thinking you're running a new, compatible version of the app.
If you tap the app now, it will crash or show an "Untrusted Developer" error. To fix this: