I've written tons of Rust and C++ over the last 6 years, both in the context of large, complex codebases with hard real-time performance requirements. I've also managed teams where I've had to 'train' new engineers and I can say that it is categorically false that Rust is easier to learn than C++, it's not even close.

From my experience, it takes any new engineer, even if they have significant Rust experience, at least 3x the amount of time to get comfortable with a new Rust codebase than it does with a new C++ codebase. BUT, once you get past a certain stage of complexity, and everyone gets accustomed to the Rust codebase, managing the Rust codebase becomes a lot easier than the C++ one.