It sounds like you're looking for a (likely a tweak, patch, or modified IPA file) for YouTube on iOS 9.3.5 — specifically a patched version that still works on that very old, 32-bit version of iOS.
Additionally, jailbreak tweaks like "DisableYouTubeUpdates" or custom API injectors are sometimes baked into the IPA to bypass the hard blocks Google places on older app versions. Significant Security and Privacy Risks youtube ipa for ios 935 patched
You can find these on archives like MTMDev or Archive.org specifically labeled for iOS 9. "good piece" It sounds like you're looking for
If you can't jailbreak:
Alex began his search by scouring the internet for any mention of the coveted IPA file. He browsed through forums, Reddit threads, and shady-looking websites, but every link he clicked on seemed to lead to a dead end. If you can't jailbreak: Alex began his search
The best working solution is a tweak called from the InvoxiPlayGames repo. It forces the last compatible YouTube version (10.11.11546) to work again.