/nIn news
They confused me by that "we never share anything but the URL" stuff.

F-Droid NewPipe really should say something like:
* Google never sees anything from you other than your IP address & the URL.

That is, Google doesn't see your account name (because it doesn't exist),
nor your subscriptions (because they're stored locally), nor your history
(per se, unless Google stores it on their servers - which they almost
certainly do but based on your IP address).