The variable in the page title is not replaced under dynamic routing

[litingyes]

Describe the bug

When dynamic routing pages are configured, if there are variables in the title of these pages, the variables are not replaced when the HTML title element is generated.

Reproduction

Expected behavior

The variables in title are replaced

System Info

System:
    OS: macOS 15.5
    CPU: (8) arm64 Apple M2
    Memory: 61.34 MB / 16.00 GB
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 22.14.0 - ~/.nvm/versions/node/v22.14.0/bin/node
    npm: 10.9.2 - ~/.nvm/versions/node/v22.14.0/bin/npm
    pnpm: 10.14.0 - /opt/homebrew/bin/pnpm
    bun: 1.2.19 - ~/.bun/bin/bun
  Browsers:
    Chrome: 139.0.7258.68
    Edge: 113.0.1774.57
    Safari: 18.5
  npmPackages:
    vitepress: 2.0.0-alpha.10 => 2.0.0-alpha.10

Additional context

No response

Validations

• Check if you're on the latest VitePress version.
• Follow our Code of Conduct
• Read the docs.
• Check that there isn't already an issue that reports the same bug to avoid creating a duplicate.

[brc-dd]

It is a design restriction currently, see #4844. Your element ID etc also won't be updated. Create a heading component and use it instead there. For level 1, you can use useTitle from vueuse. We can maybe also provide such component in future - #4867