> If you "like" them using a 3rd party client (I think NewPipe can do this) then that information is saved locally. Exactly. When you export your NewPipe data

> If you "like" them using a 3rd party client (I think NewPipe can do this) then that information is saved locally. Exactly. When you export your NewPipe data it creates a db file with all your searches, stream history, subscriptions and more. All of this happens without you having a YouTube account and this data doesn't leave the device until you decide.