Describe the bug

If I have an mpa with base /foo/ where /foo/ is an app and /foo/ext/ another app, I get the pages from /foo/ normally (I've setup the configurePreviewServer plugin), but when trying to access pages from /foo/ext/ I'm getting "Cannot GET" error. The issue is non existent when changing the base from /foo/ to just /.

Here is a minimal reproducible example with base /: https://stackblitz.com/edit/vitejs-vite-6t3tnb
And here is a fork of the same project, but /foo/ as base: https://stackblitz.com/edit/vitejs-vite-ppmfrf

Steps:
On https://stackblitz.com/edit/vitejs-vite-6t3tnb
1 - npm run build
2 - npm run preview
3 - Access /ext/ or /ext/box/form/ and verify that it works

On https://stackblitz.com/edit/vitejs-vite-ppmfrf
1 - npm run build
2 - npm run preview
3 - Access /foo/ext/ or /foo/ext/box/form/ and verify that Cannot GET /foo/ext/ or Cannot GET /foo/ext/box/form/ occurs

Reproduction

https://stackblitz.com/edit/vitejs-vite-ppmfrf

System Info

System:
    OS: Linux 5.18 Fedora Linux 35 (Workstation Edition)
    CPU: (8) x64 Intel(R) Xeon(R) CPU E5-1620 v3 @ 3.50GHz
    Memory: 965.08 MB / 15.45 GB
    Container: Yes
    Shell: 5.8.1 - /usr/bin/zsh
  Binaries:
    Node: 16.13.2 - ~/.nvm/versions/node/v16.13.2/bin/node
    Yarn: 1.22.10 - /usr/bin/yarn
    npm: 8.19.0 - ~/.nvm/versions/node/v16.13.2/bin/npm
  Browsers:
    Chrome: 104.0.5112.101
    Firefox: 103.0.2

Used Package Manager

pnpm

Logs

No response

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• The provided reproduction is a minimal reproducible example of the bug.