How have you come to this conclusion? If it was with G25, wasn't it established that it is a PCA projection that could make that conclusion by coincidence?
They could not be mixes, because they are identified separately. How could they be mixes within and of themselves, if the point of separating them is to demonstrate future generations mix among them? They did not, C5 and C4 left from the scene by late Antiquity; as determined by the study, so I don't see the point in revisiting that.
Eastern Mediterranean stopped immigrating to Rome when the empire in the west fell. Rome was repopulated with the native people who were indeed C6, which we know has existed since the Iron Age. So what you are saying is incorrect.
They could not be mixes, because they are identified separately. How could they be mixes within and of themselves, if the point of separating them is to demonstrate future generations mix among them? They did not, C5 and C4 left from the scene by late Antiquity; as determined by the study, so I don't see the point in revisiting that.
The genetic profile of southern Italians originated by at least the early bronze age, C6 represents that population, as well for much of the center. C5 is the immigrant population that arrived in the Imperial era, which seems to disappear in Late Antiquity.
It is a fact that C6 people from the Imperial age, and even the Iron Age overlap with modern central and southern Italians. This is not a coincidence, it is because they are sourced from those people. Even when comparing all of the cohorts separately in qpadm it was the only viable source.