This guide is updated on 2020-03-29 due to update of the upstream module.
The lazy way no longer works. You'll need to add the entry manually.
Android 10 has some great improvements on user privacy, but it also brings problems. One issue I faced is that background applications can no longer access the clipboard 1. This directly breaks the clipboard share functionality of KDE Connect, and that's annoying.
Fortunately, it's Android, and (at least for now) we can do whatever we want to it. And, for sure, there is a solution. There's a Magisk module called Riru-ClipboardWhitelist that can inject a list of Apps that bypasses this limitation.
The Manual Way
Using this module is quite straight forward, just install
Riru (Riru - Core) and
Riru - Clipboard Whitelist with Magisk Manager (both avaliable in the official Magisk module repository), and do a reboot.
Then, head toward a shell (JuiceSSH, Termux, whatever you like), obtain root privilege (via typing
su and allow the app to use root access), and type:
Then do another reboot. Now the clipboard sync capability of KDE Connect should work as before!