I'm waiting for official word on this if there's going to be one.
But I'm suspecting that these phones probably weren't using the original cable and wallwart combo. Especially in the second one, where although the wallwart and cable combo used wasn't mentioned, the post did tell people to use the provided wallwart and cable.
Perhaps this is a good time to remind folks that USB Type-C isn't really like microUSB. It's a more capable and intelligent port plus standard as a whole. As such, please use either the cable that comes included with the phone or third-party cables approved by Benson and/or Nathan. Same applies to wallwarts. I'd say the same for everything in general.
As for the adapter, use it with a good cable, especially the ones made by the original OEM, together with a good wallwart. Don't plug it into a random cheap cable.