Dany Hoter does some explaining:
Data in ADX (aka Kusto aka RTA in Fabric) almost always has columns that contain datetime values like 2023-08-01 16:45 and sometimes timespan values like 2 hours or 36 minutes.
In this article I’ll describe how these values are represented in ADX in Power Query and in Power BI.
Notice that I don’t just say Power BI because timespan values have different types in Power Query and in Power BI.
Read on for those details.