Raspberry pi would be a good place to start.
You should post this on the meshtastic community too.
I would go to your installed apps in settings and look for apps you don’t remember installing. A quick search will tell you what they are, then remove any suspect apps.
Long press on the notification and see what app is sending it.
At least a few 1’s I imagine.
What about Pluto from Lemmy?
I haven’t looked into the bots in years, what are you doing with them?