> They all have ads on paid tiers now.

Yup, because people who pay for subscriptions are far more valuable ad targets than people who might be too poor or too disciplined to convert on the advertised products.

And the more you pay for a subscription, and the more others purchases they can correlate you making behind the scenes once they have a fingerprint for your identity, the more and more valuable your eyeballs become, and therefore the more challenging it becomes to resist selling your eyeballs on the ad market.

Even if a service you subscribe to isn't placing obvious ads in front of your face today and promising they never will, they're 100% strategizing ways to either make the ads less obvious or to sell your data upstream so that the ads you see elsewhere are more convincing. Better hope you like buying stuff!