I was a subscriber and stopped simply because they have ads in the app. I could look past the slowness of the app than what a webpage could deliver but ads in articles for paid subscribers? Cancelled it.
The subscription fee does not and has not covered the full cost of any magazine/newspaper I'm aware as long as magazines/newspapers have existed. They've always had ads. It was just easier to look past them in print.
This pissed me off when they bought The Athletic. It was billed from day one as expensive, but ad free. NYT immediately put ads in it regardless of the fact I'd paid $50 on the basis it was ad free.
The NYT, as well as just about every other newspaper, has always had ads in the print edition whether you subscribed or not. Subscriptions have rarely paid the full cost of producing a newspaper. In the case of magazines, I would argue that the whole point of the magazine is to carry ads that target a specific demographic. The articles are just there to make you buy it.