Is DevSecOps indeed a new practice worth a professional term?
In my experience, the purpose of the "DevSecOps" (or whichever order you prefer) has mostly to do with including Security as a first-order concern of software delivery.  Security is commonly treated as a "bolt-on" (often meaning optional,) non-functional requirement.  DevSecOps attempts to describe a process where security concerns are folded into the delivery process at every step of the value stream.