I'd like to report a pretty subtle bug with Shopify's integration with Stripe. My wife was trying to configure Apple Pay in her Stripe account this week, but she wasn't able to complete the domain verification step. The form on Stripe's website kept insisting that her storefront was hosting the wrong verification code. Here's the error she got from the Stripe admin:
I've been a Rails developer for many years now--long enough to remember when Shopify was a new company!--so I understand how long Shopify and Stripe have been integration partners. I told my wife that Shopify probably hosts this verification file automatically (you do, indeed) and that it strained credulity that Shopify was somehow hosting the wrong token value (the token is, in fact, correct). Yet, the Stripe admin continued to insist the verification was invalid.
So, I did what any self-respecting programmer would do--I curled the Shopify content to a file on my machine, downloaded the Stripe file, and ran a diff. And the contents are different. Your hosted content includes a trailing linefeed that does not exist in the Stripe file. And the current validation on the Stripe side appears to be sensitive enough that this precludes Shopify domains from being configured for Apply Pay. (I ran a test from a self-hosted site and the absence/presence of the linefeed is enough to pass/fail Stripe's current validation.)
Given that this affects all storefronts, is completely opaque to customers and customer care agents, and the fix is trivially easy to implement, I'd encourage you to escalate the matter to your engineering staff right away. FWIW I will also report the issue to Stripe--their system should really be stripping whitespace characters before it compares the two tokens.
Thanks for your help! And good luck surviving another busy holiday season.