We need to document the same what we have for istio must gather in 2.x docs in 3.x docs.
The image needed in 3.x is registry.redhat.io/openshift-service-mesh/istio-must-gather-rhel9:3.1

Once the changes from https://github.com/openshift/must-gather/pull/503 are released in the core OCP must-gather image, we need to document how to use must-gather to collect info about OSSM installations. This may include links to the core support docs (https://docs.redhat.com/en/documentation/openshift_container_platform/4.20/html/support/gathering-cluster-data)

Note that the core docs list the OSSM-specific image (https://docs.redhat.com/en/documentation/openshift_container_platform/4.20/html/support/gathering-cluster-data#gathering-data-specific-features_gathering-cluster-data); once the migration is complete that should be removed.

ref. https://issues.redhat.com/browse/OSSM-10530