Seems like related issue was in Aug 2022: <a href="https://news.ycombinator.com/item?id=32572906" rel="nofollow">https://news.ycombinator.com/item?id=32572906</a><p>and might be fixed:
We just deployed a workaround that brought our site back up.
1. Find your DNS Target in heroku. It should end with .herokudns.com<p>2. Lookup the historical DNS record to get the IP addresses. You can find historical DNS records here: <a href="https://securitytrails.com/dns-trails" rel="nofollow">https://securitytrails.com/dns-trails</a><p>3. Replace your CNAME record in your DNS provider with A records that point to the IP addresses you just found.<p>Your site should come back up shortly. We plan to revert back to CNAME records once Heroku gets their DNS issues sorted.