Error message, though I'm sure everyone is seeing it by now:
Websites prove their identity via certificates, which are valid for a set time period. The certificate for itch.io expired on 9/5/2022.
Error code: SEC_ERROR_EXPIRED_CERTIFICATE
And via butler:
creating build on remote server: Post "https://api.itch.io/wharf/builds": x509: certificate has expired or is not yet valid: