Europe presumably where interchange fees are significantly lower than the US. I see:

1,4% + 0,25 € for European cards 2,9% + 0,25 € for non-European cards

I’m seeing the UK rate on Stripe’s site and the comparison is with Barclaycard’s UK POS debit rates.

In EU Stripe is 1.4% + €0.25 for European cards, 2.9% + €0.25 for foreign cards, https://stripe.com/en-fi/pricing. There have been no recent changes to this.