Inconsistent behaviour of fetcher.Form submission

[dhruvkaushik305]

I'm using React Router as a...

framework

Reproduction

this is the minimal environment https://stackblitz.com/edit/remix-run-remix-vu4mi2nx?file=app%2Froutes%2F_index.tsx

System Info

System:
    OS: Linux 6.1 Debian GNU/Linux 12 (bookworm) 12 (bookworm)
    CPU: (8) x64 Intel(R) Core(TM) i5-10210U CPU @ 1.60GHz
    Memory: 11.94 GB / 19.20 GB
    Container: Yes
    Shell: 5.9 - /usr/bin/zsh
  Binaries:
    Node: 22.12.0 - ~/.nvm/versions/node/v22.12.0/bin/node
    npm: 10.9.0 - ~/.nvm/versions/node/v22.12.0/bin/npm
    pnpm: 9.14.4 - ~/.nvm/versions/node/v22.12.0/bin/pnpm
    bun: 1.1.38 - ~/.bun/bin/bun
  Browsers:
    Brave Browser: 131.1.73.104
  npmPackages:
    @react-router/dev: ^7.0.2 => 7.0.2 
    @react-router/express: ^7.0.2 => 7.0.2 
    @react-router/fs-routes: ^7.0.2 => 7.0.2 
    @react-router/node: ^7.0.2 => 7.0.2 
    react-router: ^7.0.2 => 7.0.2 
    vite: ^5.4.11 => 5.4.11

Used Package Manager

npm

Expected Behavior

the expected behaviour is that the formData contains 3 fields: intent, otherIntent and name

Actual Behavior

commenting the prevent default completely ignores the additional formData appended and uncommenting it ignores the intent value of the button. other than creating a hidden input element with otherInten, what are the other ways of appending data into the existing formData via that handler