Voodoo behavior in Jenkins

Ok I know that when you instantiate an object of class that is non-serializable Jenkins will give you java.io.NotSerializableException, but I'm experiencing this weird behavior: When I run this Jenkinsfile, it runs without errors:

pipeline {
    agent { label 'master' }
    stages {
        stage('First') {
            steps {
                script {
                    def pattern = ~"Version-\\d+.\\d+"
                    def matcher = "Version-2.33" =~ pattern
                    println matcher[0]
                    println matcher[0]
                  
                }
            }
        }
    }
}

No error. But when I add a powershell step:

pipeline {
    agent { label 'master' }
    stages {
        stage('First') {
            steps {
                script {
                    def pattern = ~"Version-\\d+.\\d+"
                    def matcher = "Version-2.33" =~ pattern
                    println matcher[0]
                    println matcher[0]
                    
                    powershell script: 'echo hello' 
                }
            }
        }
    }
}

I get the

java.io.NotSerializableException: java.util.regex.Matcher

error. Any ideas?