For BenQ it's pretty clear according to this article, that it drops and stays as 40hz monitor when under the VRR range.For that one monitor when it is outside of the adaptive sync band, I believe it operates as it would if it was a 144 Hz monitor without adaptive sync. Hence, below 40 Hz you get Vsync at 144 Hz panel refresh or no Vsync at 144 Hz panel refresh. At least they allow you to choose to turn Vsync off if you would rather have tearing than laggy input and/or judder, unlike Gsync.
Regards,
SB
If it would work as 144hz monitor in such case it would great as it would have a more stable framerates and tearing and judder wouldn't stay visible as long.From observations and measurements I've taken, the BENQ panel 'sticks' at 40 Hz when game FPS levels drop <40 FPS. For that situation, the BENQ panel behaves like a fixed 40 Hz refresh rate display, and does what you would expect if V-Sync is on or off (judder or tearing). I will say that since it is refreshing at a relatively low rate, that the judder / tearing is more pronounced than it would be on a regular 60 Hz LCD.