It's a sad reality that we have to make these awful compromises just to ensure that we won't have any problems in dealing with cryptocurrencies and other stuff that doesn't go along/well with the regulations the government has. It's like we are still continuously being dictated indirectly by these pricks, and we gladly comply just so we don't get punished.
If you spot suspicious transaction what you can do to reverse it back?
Report it, perhaps, or do your duty (lol) to mind your own business and not meddle with other people's transactions because you'll never discern what transactions are legit and what are not in the first time you see it.
In my knowledge blockchain transaction will never be reversed unless and until destination address wanna send it back to the depositor! If you want to create any cryptocurrency it is not at all possible option for you crypto is to secure the transaction with just p2p technology.
It cannot be reversed, yes, and that's the beauty and bane of cryptocurrencies IMO. Once it's done, it's done, and one cannot give back the money that was sent if it was for the good or for the bad. It's a double-edged sword, but it has worked well for the past 10 years.