I'm not familiar with this setup, but after a quick search, it seems like it's pretty common with modern vehicles (Camaros, Mustangs, Challengers, etc.). I think the general consensus is that it is coming from either a media at the top of the canister, the machining process of the canister, or the lid that screws on.
For a catch can to collect metal through something like this, it would have to be pulling copious amounts of it from the valve cover area. Most of your PCV locations are above baffled areas of the valve covers. The
oil that's being sucked up is what's available in splash, or a vapor that's condensing.