By rule, yes, it's a personal foul.
In practice, repeated DB PFs in a chippy game that's getting out of hand can get "graduated" to UNS. None of the individual acts are specifically ejection worthy flagrant, but repeated post-whistle cheap shots are clearly distracting from the game itself. If there have been repeated instructions to knock off the post whistle shenanigans they're now violating 9-5-1f, even with "contact". By making them UNS, that's the warning shot that the next one is disqualifying.
Games like that are, thankfully, rare and you should stick to them being DBPF unless they are obviously not.