Other Layered Products use attributes in their docinfo.xml files:

https://gitlab.cee.redhat.com/red-hat-enterprise-openshift-documentation/layered-products-docs/-/blob/serverless-docs-1.33/knative-serving/docinfo.xml

https://gitlab.cee.redhat.com/red-hat-enterprise-openshift-documentation/layered-products-docs/-/blob/gitops-docs-1.15/release_notes/docinfo.xml

And there does not seem to be a rendering problem on docs.redhat. 

Investigate where docinfo.xml files for Layered Products call attributes from, and how Service Mesh can do the same.

This will make much easier for each release so each docinfo.xml file does not have to be manually updated with each new release branch.