Zend certified PHP/Magento developer

Why shows Git/Gitlab a wrong user name on verification?

Environment:

  • macOS Monterey MacBook Air M1
  • OpenSSH_8.6p1, LibreSSL 3.3.6
  • iTerm2

I try to get my SSH connections to work.
In ~/.ssh/config I have throw out all entries except of one.
I have a few key files in ~/.ssh-directory.
After creating a new key file for GitLab and adding it on gitlab.com I do

ssh -T git@gitlab.foobar.account

The answer is

Welcome to GitLab, @WrongUsername

The wrong username is a user of my private GitLab account. I’ve checked home directory – there is no global setting.
If I go to my project and do a git pull it says

remote: 
remote: ========================================================================
remote: 
remote: ERROR: The project you were looking for could not be found or you don't have permission to view it.

remote: 
remote: ========================================================================
remote: 
fatal: Could not read from remote repository.

Please make sure you have the correct access rights
and the repository exists.
FAIL

After a ssh-add the same problem.
What do I wrong?