I think that's changed: https://arstechnica.com/tech-policy/2024/01/apple-lets-devs-....

> However, the rulings established that Apple's so-called "anti-steering" rules—language prohibiting developers from mentioning cheaper or alternative purchasing options that might be available outside of an app—were anticompetitive.

> Apple has updated its App Store rules to allow developers to provide external links to other payment options, technically circumventing its normal fee structure.