In my experience, the nav on a FSD Beta car sometimes
purposely chooses routes that are less efficient but easier to drive. As an example, my morning commute to work has an obvious best path forward, and is the path that the nav had taken since I got the car in 2018. I got into FSD Beta on the initial rollout, and it was unable to make a required UPL (literally failed and quit every single time). On the next FSD update (10.3, I think?), the nav suddenly switched to avoid this turn and instead drove further up the road, making a much easier UPL that also makes the trip slightly longer and less energy efficient.
Another data point on that - I have it set to auto-route me to work in the morning. When I first get in the car, the directions show the original, more difficult UPL turn. Once I kick it into drive, though, it changes to avoid it. It doesn't matter if I engage FSD or drive manually - that's what the nav gives me regardless.
So, FSD Beta users should know that their nav won't necessarily give them the "best" route to their destination. I presume that, eventually, we'll go back to the same nav as non-beta cars once they're more confident of its abilities, but right now our navigation is on easy mode