I have installed KDE Plasma on my arch Linux but the notifications seems like XFCE4 (i also have XFCE4 installed on my Arch).
The notification configurations says: Currently the notifications are provided by Xfce Notify Daemon instead of Plasma.
Have KDE Plasma his own notification system? How can i get this?
KDE Plasma does indeed have its own notification system, but it conflicts with the one from XFCE, which is what the dialog box is telling you.
If you do not use XFCE4 anymore, you can uninstall the xfce4-notifyd package which provides the XFCE nofications.
If you do still use XFCE4, but want to prioritize the KDE Plasma notification system over the XFCE one, you can symlink the notification service to .local which should be prioritized by dbus:
mkdir -p ~/.local/share/dbus-1/services/
ln -s /usr/share/dbus-1/services/org.kde.plasma.Notifications.service \
~/.local/share/dbus-1/services/org.kde.plasma.Notifications.service
Then restart.
