Ok, good to know, could also be clarified with a rename and documentation somewhere.
Honestly that can’t be true on multiple levels:
the actual unstable branch includes upstream releases (with some minor exceptions)
“kde-unstable” exists inside of all your stable, testing and unstable repos with some version differences, so it is absolutely a divergence of this principle.
as you are an Arch derivate distro, it is confusing to use the same term “kde-unstable” for something different.
There is a reason many distros provide backport repos .
I foresee nothing but problems changing the name from unstable to git. Git doesnt have the same warning attached to it that unstable does in the minds of new linux users. Unstable warns people to expect bugs and issues. I can see lots of new linux users using a git repository thinking its safe for all systems. Then the forums swamped with posts on all the bugs and breakages they encounter.