We mistakenly used a regular Apple account instead of a Sandbox account for auto-renewing Sandbox subscriptions in TestFlight, which resulted in the subscription not expiring and failing to cancel. We reported this issue through Feedback Assistant, and Apple responded that a recent update had fixed the problem. After waiting a few days, we were able to confirm that the affected subscriptions were successfully canceled. Has your subscription been canceled as well? If you are still unable to cancel your subscription and it seems to be renewing indefinitely, we recommend submitting feedback to Apple.

Thank you for your response. I have attached the log file to the feedback report. Please investigate.

Thank you for your response. I have submitted feedback and hope for a quick resolution.