I have the same issue listed here:
The error is DNS verification failed
My site is responseradar.net , and my netlify site name is cranky-kepler-9df493.netlify.app (which works).
I am able to make A records point to a separate API site just fine, but the Netlify records do not work.
Hi, @jeffwalsh, that site no longer exists on our service. The DNS hosting for that domain is at Netlify.
However, it hasn’t been added to any Netlify sites at this time (under Site Name > Settings > Domain management > Custom domains).
Did you delete the site?
If you want us to keep troubleshooting this, please let us know. If so, what DNS records are not working and/or which site was this custom domain added to?