Unity mode is dead and gone from Fusion. It was removed from Fusion in 13.6. The latest VMware tools (12.4.5) don’t support it either (you'll find that Unity won't work if you install the latest VMware Tools release on older Fusion versions).
This also means that you'll never see Unity mode on Windows 11 ARM.
Personal opinion follows:
From what I've heard from a VMware webcast, Unity mode was dropped because it does some not-quite-standard Windows internal trickery to make it work. They seem to have viewed it as problematic to keep it working with Windows going forward.
One would think that Parallels would have the same challenges with their Coherence mode, but don't seem to. At least not that they're admitting to.
My opinion is that VMware did not want to continue to invest in the Unity mode technology because of their vision on how the desktop hypervisor products relate to their overall product strategy. They seem to want to position the desktop hypervisors as development platforms for vSphere and other cloud technologies - neither of which have any benefits for the use of Unity mode. (when was the last time you saw Unity mode in vSphere or a cloud-based instance?).