It may be coming from an issue with the Autocomplete for the checkout form. Shopify is working on a fix, but until this is fixed you can turn off the option for address autocomplete in admin/settings/checkout.
Cloudflare outage is affecting access to SOME Shopify Sites from Some locations.At approx. 5pm on 21/6/22 there was a Cloudflare outage. Cloudflare provides a performance/security layer for Shopify and many other websites.
UPDATE: here is Cloudflare’s incident report:
https://blog.cloudflare.com/cloudflare-outage-on-june-21-2022/