Are these Greece stains? Help :(

I have noticed the last few loads a couple of shorts come out with these brown / black marks that almost look like Greece stains? Has anyone noticed something similar, and any advice on how to fix would be greatly appreciated

I have noticed the last few loads a couple of shorts come out with these brown / black marks that almost look like Greece stains? Has anyone noticed something similar, and any advice on how to fix would be greatly appreciated