I am very new to linux and all the open source stuff (my first post on lemmy actually) so I don't get how this stuff works but flathub is saying that floorp is proprietary. But after a quick google search it says that floorp is open source licensed under MPL 2.0
You would be surprised that numbers of FOSS project from East Asia not having updated information/license/documentation in English.
Especially Japanese one, it's one of the hardest language that even if people had a middle level certification like JLPT N3, they might still not be able to translate formal document properly.
On other hand, FOSS project from Southeast Asia or South Asia always keeps their English documentation/license/info up to date.