It's probably due to kde connect using the same app id org.kde.kdeconnect_tp on both f-droid and google play listing, so play protect think your copy installed from f-droid is fake because it's not installed from google play yet have the same app id.
How did you install the kde connect app on your device? From Play Store, or sideloaded from another source?
It happened to me today, I installed it from F-droid.
I just went ahead and disabled Play protect.
It's probably due to kde connect using the same app id
org.kde.kdeconnect_tpon both f-droid and google play listing, so play protect think your copy installed from f-droid is fake because it's not installed from google play yet have the same app id.