I created repo as x.github.io, which I can access fine. I created another repo y.github.io in the same way but I am getting HTTP 404.

Following this doc, published the page but now the webpage is x.github.io/y.github.io. Any idea why like this not y.github.io?

Also couple more questions

1. Why I had to publish the 2nd repo and the first one was not required?
2. For both the repos, I did not create any branch but x.github.io have a master branch and y.github.io has main branch. Any idea?