Include remote template fails with 503 error

Hi, GitLab amazing people =D I am trying to reuse some Gitlab-Ci templates, and importing like the docs says here. However, on the pipeline, I am having the following error:

The doc says that for this kind of include the files should be public, in my case they aren't, so I am trying to use the project kind of include. However, this 503 error, with the remote include doesn't make clear that the error is access denied like the docs say it will be. If I was not paying attention to the docs, I would stay in this problem for a while thinking that it is a Gitlab Server error. Is it possible to change the error code? If yes, if you point me where I can make an MR.

Thanks ^^