What it looks like
A subdomain on your domain has a CNAME record pointing at shops.myshopify.com, and loading that subdomain returns Shopify's unclaimed page rather than a working site. The visible signature is a page containing text along the lines of "Sorry, this shop is currently unavailable".
Both signals are needed. A CNAME pointing at Shopify is completely normal when the service is in use. It only matters when the target is no longer claimed.
Why it can be taken over
A closed Shopify store leaves the custom domain pointing at Shopify's infrastructure. Shopify has tightened verification, but older configurations can still be attached to another store.
What an attacker gets
- Content served from your subdomain, on your domain, usually with a valid certificate that Shopify issues automatically.
- A phishing address that passes every check a cautious person would run, because it genuinely is your domain.
- Access to any cookie your main site scopes to the parent domain, which can include session data.
How to fix it
Remove the record. If you moved platforms, check for a second record too: Shopify setups often use both an A record on the apex and a CNAME on www.
The full removal steps for any provider are in the dangling record guide.
Stopping the next one
These appear whenever a hosted service is trialled and dropped, so a single cleanup does not settle it. The habit worth building is deleting the DNS record in the same sitting as the cancellation, because those are separate actions and only one of them is on anyone's mind.