I am not very familiar with this program (Kig) but it is listed as a KDE application in the website. Being a KDE program it sure has to be FLOSS, right?
Kig is listed as Proprietary
It’s probably because their appdata is missing project_license and the website assumes proprietary when it is absent. Please report it to KDE Log in to KDE Bugtracking System
No project_license mean proprietary. This is consistent with copyright in general.
I’ve went ahead and filed the bug report. Thanks for pointing me to the right direction!