Navigation is executed when using useFetcher

[bo-ri]

I'm working in an environment where I cloned MUI's Remix sample project and migrated it to react-router v7 and experiencing an issue where navigation is being triggered when using useFetcher.
Could you please help identify any potential implementation issues or points I might have overlooked?

stackBlitz: https://stackblitz.com/~/github.com/bo-ri/material-ui-remix-ts
github repository: https://github.com/bo-ri/material-ui-remix-ts

mui+remix example: https://github.com/mui/material-ui/tree/master/examples/material-ui-remix-ts