I don't see that, it reports 6.2 on Windows 10 here.
Testing further, I think the behaviour differs between the "client" and "server" processes (and I think this is not the first time we've seen this). Dumping the values from a custom action yields the results I was seeing [1].
Note that patch 1/4, as-is, will break the application that 658183a803f was fixing. IIRC we don't have any infrastructure in place to set client and server properties separately, and it's probably hard, but in lieu of that we should probably mark the test todo instead of changing the behaviour here.