QtCreator beta downloads are reported insecure

QtCreator 6.0.0 beta 1 downloads are reported insecure by Firefox 93.0. The download links are here:

https://download.qt.io/development_releases/qtcreator/6.0/6.0.0-beta1/

After clicking on the link, the download doesn't start but is enqueued in paused mode. If you click on the arrow next to the paused download for details Firefox displays a security warning (see the attached screenshot).