Ahh, I see. Well okay, you don't have to like it. But that is not the problem of the default configuration, but the problem of those who accept it as the formatting in the project. You don't like what the KDE code formatting project does, and that's the issue. Working in teams it will obviously happen at some point that you don't like what the team accepted as formatting. This is not a specific issue with KDE or rustfmt.
BTW, wouldn't it work to have your personal rustfmt configuration that you like and work with and when you are done and want to git push, it would automatically reformat with rustfmt using the teams formatting? I personally don't work in teams, so no idea if this is a viable option to do if you really dislike what they use.