Mine is shuffle.house, which seems to work for some on laptops and for the others on phones. But not consistently together. It doesn’t resolve for IP address.
shuffle.house only have IPv6 records. This means you deleted the NETLIFY records for the domain. Remove the custom domain from your site then reassign it. And do not delete NETLIFY or NETLIFYv6 records from Netlify DNS.
In that case, there is most likely an issue in Netlify’s backend. You could still try removing the custom domain from the site and reassigning it (may or may not work), otherwise you’ll need to wait for a support engineer to fix this for you.
I have removed the DNS zone and custom domain and reassigned it back using Netlify DNS. It shows a successful Netlify DNS setup. It needed about 15 min to propagate fully and now everything works well. Thanks for your help!