storybook: [Bug]: Config.base not getting appended correctly

Describe the bug

Second http-request of runtime-mjs => sb-preview is not getting config.base appended correctly in Storybook 7 when deployed to github pages resulting in a 404

To Reproduce

I am building storybook in a git workflow...

npx cross-env BASE_URL=https://xxxxxx.github.io/DesignSystem/ npm run build-storybook

^build-story in package.json
"build-storybook": "storybook build"

in .storybook/main.js

async viteFinal(config) {
    config.base = process.env.BASE_URL || config.base;
    return config;
}

First http-request
/DesignSystem/sb-preview/runtime.mjs

Second http-request
/sb-preview/runtime.mjs (404)

System

Environment Info:

  System:
    OS: Windows 10 10.0.19045
    CPU: (8) x64 Intel(R) Core(TM) i7-7700HQ CPU @ 2.80GHz
  Binaries:
    Node: 18.12.0 - C:\Program Files\nodejs\node.EXE
    Yarn: 1.22.4 - C:\Program Files (x86)\Yarn\bin\yarn.CMD
    npm: 8.19.2 - C:\Program Files\nodejs\npm.CMD
  Browsers:
    Chrome: 107.0.5304.123
    Edge: Spartan (44.19041.1266.0), Chromium (108.0.1462.42)
  npmPackages:
    @storybook/addon-actions: ^7.0.0-alpha.61 => 7.0.0-alpha.61
    @storybook/addon-docs: ^7.0.0-alpha.61 => 7.0.0-alpha.61
    @storybook/addon-essentials: ^7.0.0-alpha.61 => 7.0.0-alpha.61
    @storybook/addon-interactions: ^7.0.0-alpha.61 => 7.0.0-alpha.61
    @storybook/addon-links: ^7.0.0-alpha.61 => 7.0.0-alpha.61
    @storybook/addon-postcss: ^2.0.0 => 2.0.0
    @storybook/react: ^7.0.0-alpha.61 => 7.0.0-alpha.61
    @storybook/react-vite: ^7.0.0-alpha.61 => 7.0.0-alpha.61
    @storybook/testing-library: 0.0.14-next.0 => 0.0.14-next.0

Additional context

No response