The main proxy (invidious-based) is unstable. Google’s aggressive blocking of third-party proxies has made this nearly impossible. Most members now recommend using the mobile site or giving up on native app experience.
Fortunately, the jailbreak and sideloading communities have developed a solution: a patched YouTube IPA file specifically modified to bypass version checks and restore full video playback functionality on iOS 10.3.4. Why the Official YouTube App Fails on iOS 10.3.4 youtube ipa for ios 1034 patched
Specifically designed to hide the "Update Required" pop-up. The main proxy (invidious-based) is unstable