I have made a work profile using Shelter. I was copy-pasting some stuff in my personal profile while the work profile was disabled. Later, I discovered everything I had copied was showing up in Samsung Keyboard’s clipboard history (in the work profile). Personal profile’s Samsung Keyboard was uninstalled via ADB (among some other packages like Google Play Services). What package could be the culprit? (I’d love to just install LineageOS on it but there isn’t a built for the device yet. I just don’t use it for sensitive stuff.)
Not a full answer but yes it’s a system app. I tried to get rid of it a while back but you needed root to do it. It’s absolutely unconscionable that Samsung hasn’t given people a toggle to disable it.