It's rarer, and you can rule it out entirely by just not using types that let you leak memory. Afaik, circular `Rc` references, `Box::leak` (and friends), `MaybeUninit` and overzealous thread spawning are the only ways of leaking memory in safe Rust.
Even if you avoid those things, how does safe Rust make leaks more rare than in a GC language? Presumably leaks in a GC language or safe Rust are almost always going to be stuff like “pushing things into a vector repeatedly even though you only care about the last item in the vector”, and clearly safe Rust doesn’t stop you from doing this any more than a GC.
Note also that GC languages don’t even have the circular references case to worry about since they don’t have any need for reference counting in general.