guest user is able to create a new issue on private projects

Summary

According to the documentation, guest users of a project are able to create issues.

Create new issue ✓ (1)

the foot note (1) says

(1): Guest users are able to perform this action on public and internal projects, but not private projects.

When I add a guest user to a private project, the guest user is still able to create new issues.

Steps to reproduce

1. create a private project
2. grant another user "guest" permission to that private project
3. impersonate (or login) as the "another" user, go to the private project and create an issue.

What is the current bug behavior?

A guest user can create an issue on private projects, but according to the documentation that should not be possible.

What is the expected correct behavior?

Create an issue must be denied for guest users on private projects.