git clone git@github.com:brillout/reprod-vite-preview-bug
cd reprod-vite-preview-bug/
pnpm install
pnpm build
pnpm demo:preview

Same as single line (copy-paste me):

git clone git@github.com:brillout/reprod-vite-preview-bug && cd reprod-vite-preview-bug/ && pnpm install && pnpm run build && pnpm demo:preview

Go to localhost:3000/about and observe:
Actual behavior: 404.
Expected behavior: dist/client/about.html should be served.