I recently picked up a 2020 Epoch NPB insert card of Munetaka Murakami off of Ebay. Besides the attraction of picking up yet another Murakami card, I also wanted to see an example of an Epoch insert card. You'll notice the big silver shape behind Murakami - it may not come across well in the scan but it's silver foil. And I knew that for sure when I turned the card over because the back of the card actually says it's a "Silver Foil Insert" card (#SF-47):
There's probably something to be said for not bothering to come up with a theme for insert cards like BBM does and just labeling them "Silver Foil" or "Hologram Foil".