I have one of those, and I learned about this when I created a github.io site. I...

maxh- on Aug 21, 2021 | parent | context | favorite | on: Golang.org will be merged into go.dev

I have one of those, and I learned about this when I created a github.io site. It worked fine on Chrome in Windows, but Firefox read the SSL cert as invalid. It took me a while to figure out that it was the URL that was invalid.