There were loads of ps4 & xbox players in the warzone game i jumped into
Terrible reaction speed (turn speed) up close but pinpoint accurate at distance
What input method were they using? It shows you in the lobby with the icons to the right of their name.
Matchmaking prioritises matching KBM with KBM, controller with controller. It will mix if required to create a lobby in a reasonable time as no one wants to be sitting waiting for 10 minutes because there's not enough KBM users in their region to create a reasonably balanced lobby.