Once it all fits together it's obvious, but they segmented it quite a bit.
They even have the technology to print the pen mark for "Biden" for example and make it seem passable to the human eye, but in reality leaving behind what tech people call a kinematic artifact proving that a computer did indeed mark the candidate circle and wasn't done by hand.
Here is a video explaining the printed vs hand marked ballots:
Jovan Hutton Pulitzer Testimony @ GA Senate Judiciary Committee https://www.youtube.com/watch?v=_PpyoYlGqBg