169.254.169.254 is the AWS VPC DNS address. It might be used on some others providers as well but creator had some blog posts with AWS[1], so I assumed the he uses it.
good eye. this app is running on GCP Cloud run, and they use a similar design. I'll look into the fix.
thanks
The 169.254.169.254 DNS mentioned on the details page is also a local address. It's probably their internal DNS, so an fd00:: could also work, supposing they have one...