[ndr42]

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).

[toasty228]

Your question implies someone "designs" things and given the state of the apple app store I'm not sure any form of conscious life is in charge of it

[valzevul]

Generally it means that yes, the price will stay as-is. When the developer increases the price (versus introducing a different payment tier), they have two options: either keep all existing subscribers at the current price, or offer them to agree with the price bump (users can decline though). Reducing the price affects all existing users automatically.