I think that right now it is easier than ever to rewrite your app in Rust, due to LLMs. Unfortunately there are still people out there who dismiss this idea, and continue having their back-end written in much inferior languages, like JavaScript or Python. If your back-end is written in Java, you aren't even in the worst spot.
"You think" is cheap, try doing it, rewrite an existing library in rust and see how it goes. Doing a rough prototype is easy, but the real work starts after that.