I noticed this trying to get to the Heroku homepage, then checking another couple Heroku hosted sites I know of. Neither this nor the prior DNS issue affected our applications using CloudFront however.
We had a site on CloudFlare lose its DNS settings earlier, I seem to remember them emailing us about upgrading their DNS systems so maybe it's all related.
Interestingly, one of our Vercel apps was down too (got alerts for both app.codecrafters.io and codecrafters.io at the same time) - might've been a wider DNS outage? Resolved in 4 minutes for us.
They are a DNS hosting company that has been there for like, forever, since the days of zoneedit. Think AWS Route53, but run by a different company that only has that product. Clever name, "NS1", named after the ns1, ns2. etc domain names that are used for nameservers.