With the cost rise in raw beef, the only way to break even on it is to let the inferior processors grind it. Probably in your case an orange tub carrying raw beef got accidentally dumped into the grinder.. but for the pieces to be 1/2 inch, they were probably grinding chili-size.
Both these recent cases are suspected ball bearings blowing out and falling into the massive grinder.
If metal detectors were being used, they would have caught it both times.
grind your own. I haven’t purchased “ground beef” in years and grinding it only takes a few minutes and it tastes so much better.