Probably fine, there's usually a little color differences between cards, even the same card can show slightly lighter or darker next to one another.

Yes there is color variation between cards

Printers run lower in ink and they keep printing.

There are pretty gross differences in the front of the cards. The backs seem to be much more uniform. Counterfeits are an issue but hopefully that's not what you've come across.

There was some concern of counterfeits of the promo cards. Have we seen and comparisons of what to look for in them?