I experienced this as well, but just one time from 18th September (when I received it) until today, it appeared while it got charged while I was driving my car. But since it hasn’t appeared again in meantime, I hope it was just a software bug and nothing physical.
I just got the same alert after disconnecting the phone from the charger. The notification remains active and cannot be removed.
Update: after 15 minutes I tried to charge again and the notification automatically changed, this time saying that debris or liquid were no longer detected and that the USB port was usable again.
I got the same message, but only sometimes when connecting to my car, which android auto stopped working too. It didnt even charge my phone anymore (other phones work ok, I tried several cables too). The message dissapear after a few connect/disconnect the cable or a reboot.
My phone is in pristine condition, never habe been near water or high humigity environments,… to sum it up: android auto stopped working (a few days ago), then sometimes this message appear (first time today).
I’m able to charge (official charger, powerbank,…) and transfer files without issues. To me it looks related to the android auto usb communication (the car didnt get updated)
I’ve seen this message now, too, however I must admit that it was quite accurate: I had the phone in my pocket during cycling, USB-port up with a charging cable in it. I had a short rain shower (not much) and when I stopped later on to put the audio jack adaptor in I got this message. Removed it, briefly checked the port, plugged it in again, liquid and debris were gone it said.
since few days my phone automatically disables usb (C) port, notifying that debris or water are detected.
This happens whatever the usb cable and the source to which it is connected (computer, charger, usb port…). When the cable is unplugged, the phone says that the problem is solved…but it blocks again the port if replugged.
This makes impossible to charge the phone if switched on, and the transfer of file via usb.