How does the source code compilation work?

[Vinamra7]

I am trying to understand the project structure of Zen Browser.
In the engine\browser\components\newtab\content-src\components\Search\Search.jsx file, I removed the entire JSX part.

Before:

After:

However, after building the code and testing, I can still see the search box on the new tab page. Why aren't my changes being applied?

The command I used to build was:
pnpm build && cd engine && python mach run --noprofile

Apologies if my question seems naive. sorry 😢