Gitlab runner acces to the trigger repo

I have a shared runner we have been using for some time only in one repo without any issue (well, we runned ot of space on the runner, but that is unrelated).
I wanted to use it for several repos. The one repo is still OK, in all other the pipelines fails

Running with gitlab-runner 15.10.0 (456e3482)
  on gitlab-latex-runner gryU5_uD, system ID: s_ee3edac91bd7
Preparing the "shell" executor
Using Shell (bash) executor...
Preparing environment
Running on latex-runner...
Getting source from Git repository
Fetching changes with git depth set to 20...
Reinitialized existing Git repository in /home/gitlab-runner/builds/gryU5_uD/0/documentation/sandbox/.git/
remote: ========================================================================
remote: The project you were looking for could not be found or you don't have permission to view it.
remote: ========================================================================
fatal: Could not read from remote repository.
Please make sure you have the correct access rights
and the repository exists.
Cleaning up project directory and file based variables
ERROR: Job failed: exit status 1

Now the sandbox is in the same group as the one repo which works. The working repo does not have any direct members, all users with acces has acces to the entire group.
The runner is shared and shared runners are enabled in the repos in question. I am clearly missing sth obvious regarding token/acces settings, I am failing to find out what though.

The error says there is no repository or dont have access to the repository. That obviously point out that it could be an access restriction.

The runners are getting triggered but i feel it is unable to clone into the workspace.

It is worth to check the access token and verify if it is created in a group level or at a project level.

i got that, unfortunatelly I have to admit my understanding of gitlab tokens are a mess.

There is the token for the runner validation (which is deprecated, according to the docu) which is stored in the /etc/gitlab-runner/config.toml file and separate from the acces token, right?
So… how do I find out what acces token is the runner using and what is it’s scope?