ReservedConcurrentExecutions for function decreases account's UnreservedConcurrentExecution below its minimum value

in the serverless.yaml I’ve set reservedConcurrentExecutions to 5.

Yet I continue to get this error when I try deploying. I’d appreciate any insight.

ServerlessError: An error occurred: SubscriptionsMatcherLambdaFunction - Resource handler returned message: “Specified ReservedConcurrentExecutions for function decreases account’s UnreservedConcurrentExecution below its minimum value of [10]. (Service: Lambda, Status Code: 400, Request ID: f0182875-14ba-48a4-afb7-6e3ec9c90312)” (RequestToken: 4e849a11-4bb9-c6b0-d178-bd0723e7152c, HandlerErrorCode: InvalidRequest).