What kind of multi-tenancy are you trying to solve that Kubernetes namespaces cannot?
"Multi-tenancy in Kubernetes: implementation and optimization" - https://www.cncf.io/blog/2022/11/09/multi-tenancy-in-kuberne...
"...As we can see from the above discussion, the sharing of Kubernetes clusters is not an easy task; multi-tenancy is not a built-in feature of Kubernetes and can only be implemented with other projects’ support in tenant isolation on both control and data planes. This has resulted in considerable learning and adaptation costs for the entire solution. As a result, we are seeing an increasing number of users adopt multi-cluster solutions instead..."
It's functional, but I think it's not as polished as the rest of Kubernetes which is why Kubernetes has a multi tenancy SIG that spawned the hierarchical namespace controller (https://github.com/kubernetes-sigs/hierarchical-namespaces) and virtual clusters (https://github.com/kubernetes-sigs/cluster-api-provider-nest...)