Preview Label not appearing in Marketplace when uploading with VsixPublisher

[ShawkyZ]

Hi there,
We have encountered an issue when attempting to publish a Visual Studio extension through our CI/CD integration. The "Preview" label is not appearing in the Marketplace UI as expected.

Example:
Visual Studio Marketplace

Our pipeline utilizes a GitHub action that runs VsixPublisher.exe to handle the publishing process.
The Github action does this:
await exec.exec("${vsixPublisherPath}" publish -personalAccessToken ${PUBLISHER_ACCESS_TOKEN} -payload ${EXTENSION_FILE} -publishManifest ${PUBLISH_MANIFEST_FILE})
https://github.com/cezarypiatek/VsixPublisherAction/blob/309123e451bfde5258df748f854469b7a9155d38/src/main.ts#L68

The extension manifest file (extension.vsixmanifest) contains the
<Preview>true</Preview> element, which should indicate that the extension is in preview state.

Example release with the .vsix file:
GitHub Release

We also noticed that when uploading the .vsix file via the Marketplace webpage, the extension is correctly recognized as being in preview.