Funny, the Amex on my Pixel Watch stopped working only a couple weeks after the physical card expiry.

It was quite confusing, because a) I received a replacement physical card several months before the card expiry, so by the time my watch stopped working I'd entirely forgotten about it, b) there's no indication anywhere in the Android/Wear OS of what the expiry date is or that it might be expired and c) there's no indication at the point of sale that the virtual card is expired, simply a generic "Declined" message.