There seems be be mixed information and I couldn't find any official source to confirm this.
From the kubernetes changelog, it seems that cAdvisor web UI which has been available via kubelet has been deprecated:
The formerly publicly-available cAdvisor web UI that the kubelet started using --cadvisor-port has been entirely removed in 1.12. The recommended way to run cAdvisor if you still need it, is via a DaemonSet.
But this Stackoverflow answer indicates that UI itself has been deprecated:
Despite its UI has been deprecated it is still possible to monitor your containers via Prometheus.
From looking at the official documentation, I find no such information.
So my questions is:
It doesn't look like web ui itself is deprecated.
It's only been removed from kubelet, that's all. It means that the web ui won't be a part of a kubelet anymore.
You can still use it if you want by deploying cAdvisor as separate application.