I bind a custom domain finisky.eu.org to the github pages finisky.github.io and then remove it. However, when I visit finisky.github.io, it always redirects to finisky.eu.org which is unavailable. I suspect the issue is caused by cache.

First, try to clear/flush the Chrome DNS cache . Just go to chrome://net-internals/#dns and press Clear host cache:

However, when I access finisky.github.io, it still 301 redirects to finisky.eu.org.

If I access finisky.github.io by Edge/IE/curl, everything works fine. Visit https://finisky.github.io/?xx is also fine. So the issue is caused by Chrome.

Use Chrome F12 to debug:

It clearly shows that the website is loaded from disk cache.

Right-click the item and press Clear browser cache, done!

Reference: # Troubleshooting custom domains and GitHub Pages