Notably though, Keepassium from the App Store is licensed differently than the version on GitHub. Only the Keepassium team can ever actually submit to the App Store as GPL software is banned, and so they do not accept contributions so that they have the ability to submit under a proprietary license.
My reading from the License section[1] of the Keepasium README and this Stack Exchange post[2] is that the author of KeePassium wishes to license KeePassium under GPLv3. Accepting applications licensed under GPLv3 would require that Apple provide certain forms of source code alongside App Store downloads which they are unwilling to do. As such the App Store terms of service has terminology stating that you give Apple the right to not do that, which is something that only the copyright holder(s) of a work can do. The simplest way to have clarity over who holds the copyright is to have a single author. So long as the KeePassium author is willing to assign Apple the permission implicit in submitting to the App Store, that’s fine. It just means that all other uses of KeePassium must follow the GPLv3 license.
I am not a lawyer, nor really even well-versed in IP law, and you should not take this as legal advice.
Yes, you got it right. The source code is published under the GPL, but App Store ToS impose additional restrictions that are incompatible with the GPL. So we have to dual-license the project, and only the copyright owner can do that. In order to maintain that role, we can only accept contributions with a CLA (two pages of legalese that transfer the copyright). This is obviously a deterrent for contributions: over the 5 years, I believe there were only 3 people who signed it :)
