I had this exact thing happen on a recent order.
Mouser seem to be skimping on packaging lately. I had two heavy 105x66mm filter caps packed together in a single thin sheet of bubble wrap, which were free to bounce around, scratch each other up (not cheap parts), and crush a smaller cap entirely. It's not a problem/defect with the caps, and not even shipping-related (box was perfect externally). At least in the cases I've seen it's 100% caused by poor packaging, which is on mouser.
Unfortunately for those outside the US, service isn't always the best. After sending photos of crushed parts I was told "it's just a scratch, get over it" by Mouser Hong Kong (which AU gets redirected to), and I had to create a little storm of firm emails to US and EU specific email addresses before I got a convenient "this wasn't our fault, but we'll re-send your order this time" from the same guy who snobbed me the first time. Clearly someone had a chat to him.
I honestly expected better service from a large company, like others here I use mouser a lot. I blame Mouser HK, I suspect US HQ would have better customer service, but global consistency is still on HQ and it's no excuse. All I can say is if you don't get a fair result first go, pursue it until you do.