I think this is outrageous and I fully support uninstalling this app and leaving a bad review.
However, if you really cannot go without this app, android has a very easy-to-use notification control system. Depending on the app, you may even be able to only turn off ad-notifications while keeping all the other proper notifications working. Just long-press on any notification from the app to access the settings
No user is ever going to ask for a "quick pay" feature. That's such a corporate thing to implement to incentivize users to purchase as conveniently as possible