To support ISO 8601 basic format (the one without : ) open a specific feature request.
Sorry, I’m confused and don’t want to create another bug/FR unless necessary. This is a specific feature request for ISO 8601 in Properties, regardless of the specific string format used, and not a request for partial ISO 8601 standard support.
Additional ISO 8601 information from Wikipedia:
As of ISO 8601-1:2019, the basic format is T[hh][mm][ss] and the extended format is T[hh]:[mm]:[ss].
So a time might appear as either “T134730” in the basic format or “T13:47:30” in the extended format.
If no UTC relation information is given with a time representation, the time is assumed to be in local time.