This is an error with the certificate that is installed on your host camunda-zeebe-gateway.
The certificate has a different hostname associated to it, but doesn’t list a Subject Alternate Name that matches camunda-zeebe-gateway
This can OFTEN be related to using DNS search. for example if your nodename is actually camunda-zeebe-gateway.cluster.client.internal and you have DNS completion on so that your nodes can reach out to camunda-zeebe-gateway, the two names don’t match completely, so the certificate fails.
As is documented in the solution to External Elasticsearch configuration in self managed - certificate mismatch error
If you rebuild the certificate for your gateway including all the known names, and load that certificate it should start working.