The fact that the 25 BTC coin's holo is not completely destroyed (looks to be only peeled slightly) and yet it HAS been swept, to me, points to some solvent being used to try to compromise the coin without detection. This was performed at Defcon several years ago and it took all of 10 minutes.
I am not trying to spread speculation, but please can someone answer how else this could happen? Whenever I've peeled a coin, it is completely destroyed. It looks nothing like the coin pictured. Compare to the other 2013 Cas Brass pictured - that one looks normal.
I thought the same thing at first as it does look a little like the holograms I've solvent removed, but I think the coin was already swept when OP bought it. (I did some snooping.)
Also, if you were going to solvent remove holograms, you'd practice on some 1 BTC coins first, not butcher a 25 BTC
I've never peeled a cas though so take my opinions with a grain of salt.