Probably a mix of plastic and metal: Full metal cards don’t actually support contactless interfaces!

Two common ways of getting around that is to either sandwich a plastic part containing the antenna to a metal one, or to punch out a circular part in the middle of the metal card and put the antenna in there (and close it all up using more plastic).

One card that doesn’t do either is the Apple Card – and as a result, you can’t tap it!

> Probably a mix of plastic and metal: Full metal cards don’t actually support contactless interfaces!

Well it's really annoying: the "metal" card (maybe as you say a mix of metal and plastic) is harder to swipe, so I got use to present it face down instead of face up, for I noticed that that way I get a better percentage of success on the first try.

I don't have the problem with my full plastic credit/debit cards.

Yeah, the sandwich-type cards usually have one preferred side for contactless taps. That's one advantage of the cutout-style cards, I suppose, but I haven't seen many of these lately.