Proprietary vs Open source label

There is now a handy search filter to seperate open and closed/proprietary software.
But I cannot find any info on a sofware page if it is closed source or open.

Take this example : Boxy SVG | Flathub
It is not clear anywhere if this is a proprietary app or not (it is, moreover a paid webapp).
There is a link to the license but it could be made much more straightforward in the description (moreover the license link points here to a page that does not open in firefox…).
Am I missing something here ?
Maybe reuse the same heuristic and info than in the search database to display a open/proprietary badge ?

Any license field that links out to a different page means, that it’s a proprietary app, as they could not set the license field to an open source license string. Free licenses will be shown directly.

When we start showing the safety box, you will also be able to check there