The Ultra variants of the M series chips had previously consisted of two of the Max chips bonded together.

The M5 generation Pro and Max chips have moved to a chiplet based architecture, with all the CPU cores on one chiplet, and all the GPU cores on another.

https://www.wikipedia.org/wiki/Apple_M5

So what will the M5 Ultra look like?

If you integrate two CPU chiplets and two GPU chiplets, you're looking at 36 CPU cores, 80 GPU cores, and 1228 GB/s of memory bandwidth.