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 can try Waterfox, its also a firefox based browser focused on privacy, if you cannot definitively determine the license.
Actually waterfox seemed really interesting for me. Because the icon was very nice on top of all the privacy options.