👋🏻 Hey @Matt Atherton, welcome to Figma Forum!
This may explain what you’re seeing — removing users makes their paid seats available to reassign for the remainder of your billing term. Reducing the number of seats for your next annual term is a separate step.
On an annual Professional plan, the renewal controls are available during the 30 days before renewal. Since your renewal is November 8, try opening your team’s Admin → Billing page and looking for the renewal banner. Select Review seats to adjust the unused seats included in your next term. More details here: Manage billing on the Professional plan → Adjust number of seats at renewal.
I’ve also opened case: 2235633, on your behalf with Customer Support so they can review your account and help with the seat adjustment. Please reply to that email with the requested details, including a screenshot if the renewal controls are missing or won’t let you reduce the count.