https://wccftech.com/imac-pro-feature-12-core-upgraded-m1-max-chipset/

The M1 Pro and M1 Max caught everyone's attention by delivering astonishingly fast performance while touting impressive power efficiency. Running in the 2021 MacBook Pro range, Apple would need to create a balance between long battery life and up the ante when necessary, but that also meant leaving some performance on the table, if not all. With something like the iMac Pro that requires a wired connection all the time, you can give it all the performance it needs. According to one tipster, Apple intends to do exactly that by giving it an upgraded M1 Max, one that features a 12-core CPU.

Where the M1 Max was limited to a 10-core CPU for the 2021 MacBook Pro family, Dylan comments on Twitter that Apple will move beyond this chipset and include a 12-core CPU configuration for the iMac Pro. He claims that this information was tied to a code snippet referencing the iMac Pro and according to rumors, its internal naming is the same since it is a product targeted towards professionals.