This is a reproduction of an issue I encountered on vite 4.3.2 and vite 4.3.9. With the dev server, if the server has to serve a page a path like /sites/example.com it will 404. /sites/example.com/more works OK though.
You can see the code I added in src/App.tsx. Everything else is standard output from the yarn create vite --template react-ts command.
yarn install
yarn dev