I don't understand the relationship between your Pipeline script that and the git plugin. None of the statements you listed are actually using the git plugin or the GIT_URL variable. Can you explain further?

My mistake. I did not read carefully enough. You're using the GIT_URL environment variable in the Pipeline statement. That is from the git plugin.

I can't duplicate the problem. I suspect that someone changed the job definition to use a new URL to fetch the repository. I see the GIT_URL without username if the Bitbucket URL that I provide does not include the username. I see the GIT_URL with username if the Bitbucket URL includes a username.

Steps I took while trying to duplicate the problem:

1. Create a plugins.txt file that uses the plugin versions that you mentioned and plugins that I commonly use
2. Create a run-jenkins.sh shell script that downloads Jenkins 2.452.1 and the plugins listed in the plugins.txt file
3. Run the run-jenkins.sh shell script and complete the setup wizard by creating a new user and installing no additional plugins (since they are already installed)
4. Define a Pipeline job that clones a public Bitbucket repository and reports the value of GIT_URL using the clone URL suggested by Bitbucket and confirm the GIT_URL includes the username

   pipeline {
       agent any
       stages {
           stage('Checkout') {
               steps {
                   script {
                       result = checkout scmGit(branches: [[name: 'master']], 
                                                userRemoteConfigs: [[url: 'https://markewaite@bitbucket.org/markewaite/git-plugin.git']])
                       echo "git URL is ${result['GIT_URL']}"
                   }
               }
           }
       }
   }
   

5. Modify the Pipeline job to clone from a Bitbucket URL that does not include the username and confirm that GIT_URL does not include the username

   pipeline {
       agent any
       stages {
           stage('Checkout') {
               steps {
                   script {
                       result = checkout scmGit(branches: [[name: 'master']], 
                                                userRemoteConfigs: [[url: 'https://bitbucket.org/markewaite/git-plugin.git']])
                       echo "git URL is ${result['GIT_URL']}"
                   }
               }
           }
       }
   }
   

Hi Mark,
thank you for spending time trying to reproduce this.

Maybe my description of the issue wasn't clear enough - the version of the Git plugin that caused the username to be included in env.GIT_URL is 5.2.2.
I'm using the Bitbucket branch source plugin configured to use Bitbucket cloud for the Jenkins job in question, and it doesn't allow the git url to be manually specified (you specify things like repo name, owner, credentials, etc, separately), thus somebody (a person) couldn't have changed the url to include the user name.

The Git plugin provides GIT_URL, but the change that caused the url to be different might be caused by one of the other plugin updates, I guess - it seems pretty complicated how they all depend on each other.

I've attached a full list (jenkins_plugins.txt) of plugins currently installed - this configuration includes user name in GIT_URL