MAVEN_SLAVE_IMAGE environment variable is only taken into account on first deployment of Jenkins

Issue

• When deploying Jenkins on our OCP platform we created two custom images based on the Red Hat base images: jenkins master custom image and maven slave custom image. Environment variable MAVEN_SLAVE_IMAGE is only taken into account when creating the project. If we set the variable after the first deployment, it's not used. The configured image is always the Red Hat image or custom image configured during the first deployment.
• How do we update this image, after the first deployment? Is it normal that the value of the environment variable is no longer taken into account after the first deployment?