You have to do multiple steps to make a purchase so you must have done those and Apple considered those to be your agreement to purchase the subscription. Once purchased, you have to cancel the subscription. You cannot get out of this at any intermediate stage unless the content is not available or is defective. Refer to Legal - Apple Media Services - Apple
Apple makes no mention in its support articles about a time limit for requesting refunds, but from what others have posted through the years in similar situation you will be lucky if they will give you a refund at this stage. You have, after all, had access to the subscription for several months now. I think if you had paid, canceled the subscription then also requested a refund all at the time this happened then you would have stood a better chance. You can try now, if you wish (of course you have to pay first). Use this link to read about how to learn "How to cancel a subscription from Apple." - If you want to cancel a subscription from Apple - Apple Support
Request a refund for apps or content that you bought from Apple - Apple Support
If you want to see purchases that you made more than 90 days prior, "tap Last 90 Days, then select a different date range.
Until you resolve this with Apple, you will not be able to do any more activity through the App Store.
You can contact Apple about this but it wouldn't surprise me if they just tell you something similar.
Refer to this page for Apple Support features ➔ Contact - Official Apple Support
Select from the presented options until you find a solution for your issue, or see if there is a chat or phone call contact method offered lower on the page under “Get more help” (you sometimes have to narrow down the options multiple times before this is shown). If you do not see your issue, keep experimenting with any series of selections until you reach one that offers a chat session or a telephone call and get the representative to redirect you.
This support article has various country telephone numbers for contacting Apple for support and service ➔ Contact Apple Support - Apple Support Scroll down to “Connect with live support”. If your country is not in the list, do to the “Other countries” entry at the end of the list. Not every country has telephone support, and phone numbers may only work when calling from the same country.
For chat, you can try using the Apple Support App —> https://apps.apple.com/app/apple-support/id1130498044
