Hi @won changsub — welcome to Figma Forum and thanks for raising this. Just a quick note: I removed some personal information from your post to help keep your account details private.
I can't access and share out account specifics here, but I do want to make sure this gets resolved as soon as possible. I went ahead and opened a ticket on your behalf with our Product Support team. Your case number is: 1819056, and they will be in touch with you as soon as they've had a chance to review.
In the meantime, it's worth knowing that Figma's standard policy treats subscription payments as non-refundable — but our Support team reviews accidental upgrade situations on a case-by-case basis, so please do watch for their response. In addition, this article outlines how subscription downgrades work in case it's helpful for the future: Upgrade or downgrade your plan → Downgrade or cancel your plan.
Please keep an eye on the email inbox tied to your Figma account for more. 🙏🏻