I just went out and tried mine, in various driving modes. 2024 SR 2LT HTC Z51.
Z Mode appears to disable the dash V8/V4 indicator, as per DW Ruby. The chart below also doesn't show it as "enabled".
I fired it up in the driveway, and switched from D to M, and the V8 indicator stayed visible on the dash. I didn't drive it, so it may just stay on as "V8" when in motion, no AFM. Will test that theory tomorrow, or next time I get a chance.
Page 201 on the 2024 PDF OM suggests that "Track" mode also disables AFM, per this chart.
UPDATE: Tried the Manual Mode shifting thing this afternoon (in the rain), got onto the local 402 freeway, accelerated to 50, 60, 70 MPH (sorry, I'm to old for metric) and then just put the CC on at each speed. The dash V4/V8 indicator stayed on V8 the entire time. Under no load, flat road, not inclined, calm wind, mostly dry highway. In D, I'd be seeing V4.
So, I would conclude, as others have stated, MM does disable AFM. Unless the sneaky bastards at GM programmed it to change to V4, but left the V8 icon active.