Most jobs have started incrementing their build numbers by 2.  A few jobs have started counting by 3.  I thought it may have been folder related as one of the jobs that was counting by 3 was a bit deeper in a folder, but in further testing, a test job was counting by 2 no matter if it was 5 folders deep, or in the root of Jenkins.

Test job which is counting by 2 is built with this Jenkinsfile put directly in the editor in Jenkins so no SCM involved
pipeline{
    agent{ label 'master' }
    stages{
        stage("test"){
            steps{
                echo "test"
            }
        }
    }
}

Testing a freestyle job which also just did an echo and everything was sequential