This sure sounds like a rumor that started with Ainge and the Jazz to try and get the Knicks to increase their offer. Almost none of the teams rumored to be going after Mitchell make much sense.
Washington has Bradley Beal. I don't see he and Mitchell as an ideal backcourt, but they do have some young players and picks to offer. Miami doesn't really have any trade bait beyond Duncan Robinson's contract and maybe Herro. And Mitchell doesn't seem like a Heat type player to me. I definitely don't see Ujiri and Toronto offering a bunch for Mitchell. Charlotte makes some sense if Rozier dealt in the deal, either to Utah or a 3rd team. But while Miitchell and Ball are seemingly a good fit on paper on the offensive end, that might be the worst defensive backcourt in the NBA, including the Kings. Atlanta just gave up the farm for Dejounte Murray so they don't have draft picks to offer and why on earth would they trade all that to pair Trae Young and Murray and then deal for Mitchell?
As for the Kings, the Huerter trade tied up future FRPs and unless the Kings are dangling Keegan Murray (which I'd be against) they don't really have much trade bait for a seemingly rebuilding Jazz team. Fox and Mitchell also don't make sense to me as a backcourt.