Why am I not eligible for a refund from the App Store?

The specific terms you are looking for in the article provided by IdrisSeabright is:

All Transactions are final.

Forgetting to cancel a free trial is not a valid reason for a refund. With that said, Apple on occasion may provide a compassionate refund on a case by case basis, but it should never be expected and no reason for denial is needed. When you accepted the free trial by double clicking the side button and verified your identity with FaceID/TouchID or Passcode, it also showed the subscription start date with the price that you will be billed if the trial was not cancelled at least 24 hours before the end date. That is simply what you agreed to.

Missmanda wrote:

I forgot to cancel a subscription before the free trial was over and as soon as I got the notification from my bank that they had taken money I contacted support and they helped me put in the refund request and also canceled the subscription for me and telling me that a refund should be no problem since i caught it right away anyway now they’re saying it’s not eligible for refund due to apple policy so I asked them to show me the specific terms or condition that makes it not eligible and no one will show me one guy told me it was because it wasn’t within the 60day window which is it was the very same day idk what to do any suggestions?

Apple considers all digital sales final. Refunds are given on an exception basis. Apparently, they decided not to make one in your case.

Legal - Apple Media Services - Apple

If I download something with a free trial, I always put an entry in Calendar 48 hours before it ends to remind me to cancel it if I need to.