WhatsApp also feels... tonally weird to use at a serious company, like in the same way it would feel weird to be using snapchat for team meetings.
When trying to avoid subpoenas of data on the device itself, it's important to frequently "lose" the phone with the messages on.
In Brazil even subpoenas can be sent via WhatsApp.
The court: "No problem, just join the session on video using WhatsApp"
Remote court sessions are usually on Google Meet or Zoom