Duolingo Super Annual Subscription Charged Without Approval

I started a 7-day free trial for Duolingo Super in the Duolingo app. I was told that I would receive a reminder notification two days before the trial ended. My trial was supposed to end on June 30, but on June 29 at 11:52 p.m., approximately $21 was charged to my account without my permission or approval.

Since I did not want to continue the trial membership, I canceled the subscription on June 30, but the fee had already been collected, and my membership now appears active until June 30, 2027. I absolutely do not want such a long-term subscription or a charge of this amount.

I am a student, and this charge has caused me serious financial difficulty. My email address is t.*@Gmail.com**, and I request a full refund of the approximately $21 that was charged to my card without my authorization as soon as possible.