I'm using Fedora with KDE and I haven't seen any notifications and had no idea it did this. I'll see if I can figure out what's going on in my system and maybe it will help other people.
I asked Claude to set up notifications for itself and it did. It wasn't on by default. Claude edited some config file. For simplicity I had it play some audio file, not a KDE toast, since I mostly cared if I wasn't looking as that machine. I am also on Fedora KDE.