Custom Resolution Utility (CRU)

[Dreamic]

I don't think it's a fault of your program but something dumb Nvidia is doing and I think should be added to the Editing VRR Range section, not sure if there's been discussion about this.

In order to lower my VRR/LFC Range from 80 to 30, changing it is not enough. I must also change the Device ID to something with a lower VRR Range, like DELA179 (Dell/Alienware AW2721D 1-240Hz). Mine is SAM105C (Samsung Odyssey G7 80-240Hz).
This is the only way to go below 80Hz VRR. Reset Device ID to SAM105C and it will no longer go down to 30Hz~.
Also the Nvidia database is wrong about this display being 60-240Hz, it's 80-240Hz.
Everything is as up to date as it could be, monitor firmware included.

I don't think everyone will figure this out, why their 40fps in GSync Pendulum is 80Hz instead of 40Hz or 70fps is 140Hz, it's because of Device ID, LFC doubling isn't changed unless Device ID is to a correct one.
And we know LFC on certain displays, I think I've heard mainly VA, results in a brightness shift/flicker, as Hz jumps from 75Hz to 150Hz etc when you drop to 75fps, 85fps will be back at 85Hz. This is how you fix/mitigate this.