CSS module gets unloaded on navigation, while still needed

[Dubzer]

Which project does this relate to?

Start

Describe the bug

hii
i've found a bug, where if two pages depend on a common CSS module, it gets unloaded when navigating from the first to the second page, thus breaking the styles. i enabled ssr: false on both pages and the bug still persists, so the problem might lie within the router rather than the start

Your Example Website or App

https://github.com/Dubzer/tanstack-start-css-unloads-repro

Steps to Reproduce the Bug or Issue

1. pnpm build
2. cd ./dist && pnpx srvx --prod --static ../client ./server/server.js
3. open /
4. click to subpath in navbar
5. notice that the button has lost its styles

Expected behavior

the stylesheet doesn't get unloaded

Screenshots or Videos

No response

Platform

• Router / Start Version: 1.139.14
• OS: macOS
• Browser: Chromium
• Browser Version: 143.0.7499.40
• Bundler: vite
• Bundler Version: 7.1.7

Additional context

doesn't seem to be a recent regression

[s-r-x]

can confirm this
#6001