See, here's the "sticky" part. That device only received official OS updates to Android 5.0, which I believe is no longer supported in Google Play Services. However, if you look at the YouTube app on the Play Store it does not list a minimum Android version - it just says "varies with device". I guess it COULD be argued that the app should still be supported on that OS version, but the OS is not supported by Google anymore.
I still stand by my previous post that even with the latest official OS update for that device (Android 5.0) it's still too old. Oh, and Android 5 is now 7 years old. It also stands to reason that even if that device is NOT yet on Android 5.0 the update servers likely aren't providing that update to that device anymore.