They do Rockwell testing for example. Maybe someone got crazy after they messed up and this was supposed to be discarded. Lol. I would hold on to it to be on the safe side.
Also there this type of thing https://forums.collectors.com/discussion/906185/chop-marks-and-test-cuts so just saying anything is possible
This was all done after the coins left the mint. The mint does not do any test that would explain the OP coin.
So you’re saying that even though a number of experienced and knowledgeable collectors have said that the coin in question was damaged after it left the mint, and there is no possible way that it could occur during the minting process, you’re proposing that “anything can happen” as an explanation. William of Ocham, a 14th century monk and philosopher, once said that the simplest explanation is usually the correct explanation. Maybe it could be something that no one has ever seen before. “You never know”. But since the marks look like numerous other examples of mechanical/impact damage from circulation, I’m figuring “we do know what happened”.