[ndr42]

Good to know: My screenshot was from the web version of the app store page (see link in my first post), the iOS-version shows month or year as you said.

The premium yearly subscription has 3 price points shown (22.99, 34.99 and 44.99€) - I feel really bad for the developer as their customers are reminded that they have to pay more than others have paid before. I don't get why Apple is showing the old prices.

[MattRix]

It’s not that you’re seeing old prices per se, but rather that it’s easier to make two IAP items (one with regular price, one with sale price) than it is to actually change the price of a single IAP. That’s why you see multiple items.