IAM policy: can't specify Secrets Manager secret ARN with "/" in the name

I have a secret in Secrets Manager whose ARN includes a slash (e.g. service/postgres). This triggers a validation error in the console when I try to specify the ARN in a policy in IAM (GetSecretValue).

Removing the slash works fine, but the secret name I want to use contains a slash. I have other secrets that I've created previously that have a slash in the secret ARN. I'm pretty sure this is just a simple validation bug, and I wanted to report.