If the previous impl had known memory safety issues I'd imagine they'd fix them as a matter of priority. It's hard to test for memory safety issues you don't know about.
On the rust side, the question is how much `unsafe` they used (I would hope none at all, although they don't specify).
It is entirely possible a Rust port could have caught previously unknown memory safety issues. Furthermore, a Rust port that looks and feels like C++ may be peppered with unsafe calls to the point where the ROI on the port is greatly reduced.
I am not trying to dunk on the effort; quite the contrary. I am eager to hear more about the goals it originally set out to achieve.
You can look: https://github.com/LadybirdBrowser/ladybird/pull/8104/files?...
It seems like it is used mostly for FFI.