That's illegal in Europe. You have to be able to cancel via the same means as you signed up. So if you can signup online then you must be able to cancel online.
It probably depends on which country is handling your subscription. With a German address, they don't have to consider any request in any language other than German.
A recently passed German law requires (among other changes) an online cancel button, however companies don't have to implement it until July 2022 unfortunately.
It sure as hell doesn't work like this for the newspaper Le Monde (in France). Sure you can sign/resign with Apple/Google but if you sign with e-mail, you have to mail a physical letter to resign (8Euros one with proof of delivery and all)
Here is the Dutch implementation, because it's the first I could find in English: https://business.gov.nl/regulation/automatic-renewal-subscri... As is says there "Consumers must be able to cancel their agreement in exactly the same way as they signed up for them."
Unfortunately I don't think that's true. I'm looking at you, beer52.com! [1]
(And yes, they were doing this long before the UK left the EU, and are still at it today)
[1] https://ibb.co/r4LfK5F