Every time the new (Caldeera) Warzone anti-cheat driver needs to be updated this issue arises.
In the logs we find;
C:\ProgramData\Battle.net\Agent\Agent.7614\Logs\> ... "failed to initialize dependent op 'brynhildr_odin'"
The driver (.sys) is somewhere near that folder and Battle.net fails to (re)install it.
You have to grant the agent admin permissions (Right click → Properties → Compatibility → Run as Admin)
C:\ProgramData\Battle.net\Agent.exe
Note that every time Battle.net itself updates (and thus the Agent.exe changes) you have to set the permission again, in case Warzone needs to update the driver.
I hope this helps someone. Also Blizz, ty for banning me on h0ts, give and take right? 