[2021] Console players using chat?

All that the symbol shows is that they are on a different platform than you, so they could be Windows Store, Xbox, Switch, Stadia or Playstation - as they're able to chat (and presuming you are on Steam) that would mean they are playing from Windows Store or Stadia (I believe Stadia users can also use the in-game chat).

Players from Xbox/Playstation/Switch cannot use in-game chat even with K&M plugged in.