How can I get to know who the current user is on the GitLab Page

I run CI/CD pipeline from GitLab Page by using the API but I can’t check who starts that pipeline.
When I try to fetch document.cookies it turns out to be empty because of httponly.
When I call userinfo_endpoint (/oauth/userinfo) I get CORS error.
How can I get the necessary information or a current user token to start the pipeline?
The problem is that the trigger token identifies the user who created it, and that this trigger token is statically included in the code.
I need a token or information that identifies the user who started the request actually.
Thank you for your help