Suppose I asked you if I could borrow your car to get groceries. A week later, I take your car again and go for a road trip. You would be justified in being mad at me, because (1) the consent didn't cover the use and (2) the initial consent was for a limited time.

Google has an obligation to verify age. Google also has an obligation to limit tracking of personal information to usages that have been consented to. Neither of these obligations negate the other, and if Google never put it onto their feature roadmap, that just means that Google has been negligent in fulfilling their obligations.