Apple has a prototype for the 27-inch iMac that featured the M1 Max, but it was not the iMac Pro. There was allegedly a supposed iMac with a 27-inch display and M1 Max chip that Apple created last year as a prototype, and it features a black finish for the device.
Apple and TSMC are facing price hikes on their chips, and they may focus on more expensive devices. Apple is reportedly facing a massive price hike on its Silicon chips that TSMC creates for them, and these chips are what the Cupertino company designed for its devices, including the Mac and iPhone.