The next step should be to transform "unethical" into "illegal", except enormous business entities rely on subscription revenue.

Otherwise it's a very well know effect. There will be unsubscription peaks every time the service communicates with thei customers, even purely informative stuff like "we now have a dark mode" emails will remind people they've a subscription and some will cancel, that's part of the business and something that affects communication frequency in subtle and obvious ways.