The user searching for this query is likely holding an older Apple device—specifically an iPhone 5s, iPhone 6, or an iPad Air 1. These devices are stuck on , the final security update Apple released for 32-bit and early 64-bit architecture.
For users on iOS 12.5.7, there is only one safe, legal, and functional method to get YouTube working without "jailbreaking" the device. youtube ios 12.5 7 download apk old version