Earlier quoted context omitted.
That's 6.25GB/day over a 20 day working month. More time, less data per work day, harder to detect.
And it might be disguised as a video stream coming out of the video streaming servers. But it could also be a 128GB thumb drive plugged into the system somewhere.
Just log in to FB messenger or Discord and egress it as small data chunks that way. Lots of people have private chats on work computer for practical purposes.
Discord allows for bots, so you could easily write a script to chunk data and egress, and another to re-assemble.