Sending a file to my phone via kdeconnect produces a success notification on the sendinmg computer. Receiving a mail on the phone while at the computer produces two notifications -- via kdeconnect from the mail app on the phone, and from the mail program on my computer. So far, the only way seem to be to configure Plasma's notifications to not show notifications of the type "Generic Notifications" from KDEConnect, but that also disables all other notifications (messenger etc). I would prefer to be able to configure the apps allowed to send notifications to the computer via KDEConnect.
You can do that in the plugin settings in the Android app
All I see is a general "Notfication sync" with just on or off. No possibility to select one or more particular apps.
Clicking on that entry should open a list of applications
Ok, not really intuitive nor obvious. That UI could use a search facility.