New code accidentally leaked by Apple suggests it is still hard at work on a new Mac Pro powered by the M4 Ultra chip.

Apple’s premium desktop machine is currently powered by the aging M2 Ultra chip with a 24-core CPU and a 60-core GPU. That’s backed up by a 32-core Neural Engine.
Now, code discovered by Macworld hints at the possible arrival of a new M4 Ultra version of the machine. If accurate, this could be the first Mac to use an M4 Ultra chip.