...the non-beta software better than the beta software in this regard?...
Some people narrowly define what a phantom brake is so they "don't" have it.
For me, anything that slows my car down when it didn't before is phantom brake. Anytthing that slows my car down even with a logical reason like "Forward Collision Warning" but a human wouldn't do that so that I would classify it as a phantom brake.
Phantom brake is logical to the machine such as because its GPS coding says 35 MPH, so it logically slows down even in the 85 MPH highway zone as recorded by the camera, but it is not logical to humans.
Its logic would pass the grade with its creator but not to the police giving me the ticket, phantom or not!
The radar version has fewer phantom brakes than the radarless version.
I have 2 Tesla: One with radarless and one with radar version.
Immediately after I switched my Tesla Model 3 to radarless FSD beta, I experienced much more phantom brakes.
After 1 year, there's some improvement but it still has more phantom brakes than my Model X with the radar version.
By quitting your FSD beta now, you will get the radarless version because the radar version has not been allowed for Model 3/Y since 2022.20.9.
So whatever phantom brakes you got now for your FSD beta, you will still get them with no difference when switching to a public FSD version starting 2022.20.9 and above for your Model y.
The problem is not because it is FSD beta but because of the coding of pure vision. That coding is different from the radar version whether it's FSD or not. It's the problem created by the software team.