This is Apple's work - they show all enabled purchases/subscriptions author have enabled for price testing. And once you add one, removing it would mean the user's subscriptions auto-renew would get canceled, so they stay and accumulate.
And there is no way for the app to mark "this is the current pricing".
Does that mean if I subscribed for 22.99€ it would stay that way year after year?
What could be the reason that Apple designed it this way? The only reason I can think of is customer protection (say 1€ a month changes to 100€ a month and you user does not pay attention).