This issue was caused by an expired SSL certificate in one of the components of the RealConnect service that balances call traffic across different deployments. All other service components were properly updated in anticipation of the certificate expiration, however this one was missed.
This only impacted a subset of customers, specifically those using video endpoints that do certificate validation when calling into RealConnect meetings over SIP TLS. All other calls were not impacted.
A fix was implemented at 14:00 MDT on Apr 1st 2022, resolving the issue immediately after. Our internal processes have been reviewed and updated in order to prevent this from happening again in the future.