iOS has no apps to play YouTube without ads that are able to cast it to TV or some other chromecast device. Believe me, I tried different ones. The best way to use YouTube on iOS is through Brave browser. But there is one feature lacking - be able to cast YouTube to a chromecast device. That would be a killer feature for all iOS users, because there are no apps that can do that. Some of them can poorly play YouTube on the device itself, but no cast.