Hoping that someone knows the function of the "Slide Retainer" on the DAO models

The PT111 Millennium Pro manual calls this as the “slide retainer”; the PT111 Pro manual calls it the same and says it’s only on the “DAO versions.” I don’t see that this interacts with anything below and it appears to just fit into a cutout in the underside of the slide. Does anyone know what this actually does? And /or how it accomplishes its’ task/function. It surely slows the slide a bit but that doesn’t seem like much to do. Since the dao versions don’t cock the striker, does this take a similar amount of energy as that would typically entail? Hoping someone knows the real deal or scoop behind this little part. Thanks in advance to all who weigh in with anything of value. First pic shows the doo-dad and the second pic shows the cutout and ramp on the slide.