If you pay for it, it's not a free service, so which is it? The whole model hinges on the fact that no kind of payment is advertised, not ads and especially not tracking. (If the GDPR prompts are good for anything then at least for making this bit more obvious)

If you treat this as payment, wouldn't you require an actual business relationship with those users?

Also by that logic, Google just unilaterally altered the contract without even so much as notifying its users about it (thanks to hidden, seamless auto-updates of Chrome)

In which other segment would you tolerate stuff like this as a customer?