I have a couple of issues I believe are related regarding githubpages.
First, when trying to create my user page by naming the repo the same as my username, I expect the url to be this myusername.github.io.Instead it looks like this myusername.github.io/myusername.
I have been to work around this by naming my repo myusername.github.io, which produces the correct URL.
Now, I want to create a custom domain with this user page. I can use my custom domain with the above workaround, but this now affects all other repos which use github pages. For example, I setup myusername.github.io to use mycustomdomain.com. But now I have another project that uses gh pages called someotherproject. The url now redirects to mycustomdomain.com/someotherproject instead of someotherproject.github.io.
Is this working correctly?
This is what described in the official documentation "Supported custom domains"
That was reported as an issue in 2016:
In 2020, here is a possible workaround, mentioned by Oliver Vorasai:
Not ideal though, as mentioned by Emma Sax :