It took them a few days more, but here is 5.20.4 and KF 5.77 on the way to unstable. For me right now there is 18 packages to be removed, but I had no time to look into them. But as there are kde-plasma-desktop and kde-standard among them, I am quite sure you don't want to let them go. So please hold back for now because it seems like the upload is not finished yet.
10:00 MET: Looks ok now from here, just user-manager gets removed, as it has no version matching 5.20.x. Let it go, it'll be back after 5.20 hits testing, if you need it.