Saving variable font results in static font

[Materuilist]

Hello! Enjoying your package in multiple projects, but there is 1 blocking issue for me here.
It can be demonstrated with this simple code block in browser environment (similar flow doesnt work in Node.js as well):

async function downloadFont() {
    if (variableFontFile) {
      const url = URL.createObjectURL(variableFontFile)

      const font = await opentype.load(url)

      font.download()

      URL.revokeObjectURL(url)
    }
  }

If url points to any variable font (Open Sans .ttf in this case), then the downloaded result will only contain one variation. So variable font file narrows down to just static font file.
Is there a way to fix that, or it is just not supported yet?

Fonts issue.zip