It is not a big issues anymore, but it remains as it is.

Standard and High Concurrency Cluster have a working Spark UI,

Single node clusters do not.

I tested with runtime 9.1 and 10.1. The Runtime does not matter. It probably is the slightly different setup with the single node clusters.

Spark UI history server works in either cases.

Only interactive single node clusters are problematic to work with, all others are fine. For Jobs that complete it is not an issue.

At the moment my bigger issue is that there is no Databricks SQL and the respective dashboards in GCP. Just the Data Engineering View and Machine Learning.