Credit cards send updated card information to various merchants that you've used. Usually it's for things like subscriptions or bills so you don't have a gap in service. Personally I hate it because it lets smaller stuff slip through the cracks for longer.

For example: https://www.americanexpress.com/us/merchant/cardrefresher.ht...

Yeah. Google Pay works the same way.

There is no reason why Apple Pay should be linked to a physical card at all - they can and should work completely independently.

I also had this happen. I was pleasantly surprised. Apple Pay is easier than it used to be when it comes to registering cards too.