Hi everyone—there was indeed an issue with two of our multi-tenant Consul clusters today. We tracked it down to changing IP addresses due to some of the cluster members being migrated (more context for the migration process is here: PSA: Machine migration has started again). The migrated cluster members were serving 5xx responses intermittently.
We’ve addressed the issue and confirmed that the clusters appear to be functioning normally again. Apologies for any inconvenience this caused, and thank you to @deano-fury for posting here!