Gitlab pages redirected to gitlab sign-in page when not logged-in

Summary

On gitlab.com, using Gitlab Pages, project site redirected to gitlab sign-in page when not logged in.

Steps to reproduce

1/ Open a private browsing tab in you browser
2/ Go to https://powerstencil.brizone.org (through my DNS) or use the native gitlab URL https://tools4devops.gitlab.io/power_stencil.gitlab.io
3/ You are then redirected to gitlab.com sign-in page: https://gitlab.com/users/sign_in instead of having the site displayed.

Do it in when logged-in and everything works fine.

Example Project

https://gitlab.com/tools4devops/power_stencil.gitlab.io

This is currently a private repo, but if really needed I could give access to. This is actually just a static page, there is absolutely no reference to gitlab.com in it. It is easy to verify by accessing the site while logged-in...

What is the current bug behavior?

If you are not previously logged-in into gitlab, you are redirected to gitlab sign-in page instead of having the site displayed.

What is the expected correct behavior?

To have the site correctly displayed even when not previously logged in into gitlab or in private sessions browsing.

Relevant logs and/or screenshots

This is how the site looks like if logged-in into gitlab.com when_logged_in

This how it looks like when in a private session browsing (redirected to gitlab.com sign-in page): when_not_logged_in

Output of checks

This bug happens on GitLab.com

Possible fixes

(If you can, link to the line of code that might be responsible for the problem) Sorry...

Edited by Laurent Briais