Looks like it went through a mechanical impression device. Could be many things, leather softener, etc.
It is Post Mint Damage, so what ever caused the damage really doesn't matter and is pure speculation. Just know, the coin did not leave the mint in this condition. Welcome to CT. Note that when you post future coins for opinions, we like photos of the reverse and the obverse.
I doubt there is anyone on here doubting PMD. I thought it was fair enough to ask if anyone may recognize the pattern of damage on the coin. I have seen machines than you run newly tanned leather through that make similar marks. Tough machines, (tough leather), and it MAY be the cause here. Of course, many machines do similar things, such as wire length counters, etc.
Oh. Not being snarky, but 'Anyone see this before', would have alerted me there was a question. My bad.
No offence taken here any suggestions as to how to navigate and post on the forums is most appreciated.
Post as you have already done in Introductions and here in this section, at the bottom of your written text you will see the Upload a file button, click this, choose your image from your saved data files and when uploaded click on full image. This will allow members to see an enlarged image of your coin and give a more detailed reply if necessary