I posted this issue in the slack thread here: https://shopifypartners.slack.com/archives/C02F94JC3QC/p1687799668603189 - here I received confirmation that this was an issue on Shopify's end. They also were able to deploy up a fix for this shortly aft...

hey - we’ve got a Hydrogen / Oxygen headless built where the checkout is going to checkout.mydomain.com and the rest of the site is at mydomain.com. The issue is that all collections and static pages are redirecting to checkout.mydomain.com NOT mydom...