Hi Ultraseven,
We don't have plans to retire the DevOps Engineer Expert certification, nor the corresponding Exam AZ-400.
A few months ago we changed the name of the certification to reflect our vision for the job role and required skills, along with the direction we’ll take as we include additional skills in the future. DevOps Engineers combine people, processes, and technologies to continuously deliver products and services. They use built-in Azure services, such as Azure DevOps, and they can integrate with Azure using lightweight tools and features from GitHub or open-source DevOps tools.
As part of our exam and certification maintenance, we may include new skills and new technologies as they are needed by the role, and you might see changes to the exam to include additional objective domains aligned with that--we always announce these changes in the exam pages.
So if you are interested in this certification, there is no reason to postpone it.
Hope this helps!