There 's a few special notes about subscriptions in the article If you want to cancel a subscription from Apple - Apple Support
"If you don’t see Cancel Subscription, then the subscription is already canceled and won't renew." An "Expires" date (instead of "Renews") means the current subscription will just run until then. "Resubscribe" is just in case you change your mind about having it end. If you need to stop it immediately you will have contact Apple.
Also a section at the end about iCloud subscriptions.
"Can’t find the subscription that you want to cancel?"
If you still can't find a subscription, contact Apple Support using this issue-specific link at the end of the support article. --> Apple Support