In the world I inhabit, Apple is the one that intentionally makes it really hard to cancel subscriptions. You literally cannot cancel a subscription to an iOS app from an Android phone or Linux PC.
You can't subscribe without an IOS Device , Mac or Windows PC.
If your in some strange edge case where your subscribing to services and then discarding your IOS devices before canceling , that's on you. In a worst case scenario you could borrow a friend's Windows PC. As much as I love Linux I can't imagine most Linux users don't have at least one windows PC or Mac.
If we really want to get technical, spin up an AWS instance, RDP into it, install iCloud for windows and then cancel your subscription.
There are a few services you can sign up for without any of those... but Apple has a support page telling you how to unsubscribe from those from the devices you signed up from: https://support.apple.com/en-us/HT211011
Said support page also says you can contact Apple Support about it, which I imagine would also work for the "canceling an arbitrary in-app subscription" issue.
It's not an intentional trick to force you to keep paying.
The vast vast majority of people have access to a Windows PC or Apple product. How you ended up in this edge case I'll never know.
To take this to it's logical conclusion, what if you don't run JavaScript on your browsers. Would they also need to give you a cancelation page which doesn't require JavaScript.
If your in some strange edge case where your subscribing to services and then discarding your IOS devices before canceling , that's on you. In a worst case scenario you could borrow a friend's Windows PC. As much as I love Linux I can't imagine most Linux users don't have at least one windows PC or Mac.
If we really want to get technical, spin up an AWS instance, RDP into it, install iCloud for windows and then cancel your subscription.