Can I check? Are you profiling the serving of a HTTP request using Rust there, but using the Firefox Profiler to make the output easier to read and navigate?
We've mainly been using it for tracking CO2 client side, and I hadn't seen examples of using it server side like that - tres neat!
https://www.thegreenwebfoundation.org/news/carbon-emissions-in-browser-devtools-firefox-profiler-and-co2-js/