We have resolved this incident.

A fix has been implemented and we are monitoring the results.

In order to resolve the error for the affected connectors, users will need to perform the following two steps:
- Revoke trust for the certificate associated with the failing connector by navigating to Account Settings.
- Re-run Connector Setup Tests by navigating to the Connector Dashboard -> 'Setup' -> 'Edit Connection Details' -> 'Save & Test'

Additional instructions for this can be found in our Documentation: https://fivetran.com/docs/security/certificate-verification#certificateverificationatfivetran

The issue has been identified and we are working to resolve it.