Make sure you actually know what you are flagging or writing. k3b has been kf5 based in KaOS long before you started helping with development (kf5 based since May 2014). AUR is NOT packaged, that is users adding build files, so not Arch maintained or in the Arch repos, like it is for KaOS users.
Why are you even bringing this up? Or have you never used KaOS or even looked how k3b is packaged/supplied here? Looks really like you are just abusing the flag option without have a single clue what k3b is here. Follow the links you used on the website where you flagged this package and check the git entries, then at least you would know what k3b is here.
Do not flag about what MIGHT be released, of course releases are followed here, and k3b will stop being a git checkout build here as soon as a kf5 based stable release will be done.