Mqtt add-on "Client <unknown> disconnected"

I am getting these errors in my mqtt logs every few seconds.
I disabled every add-on that was running and restarted HA and it still is happening. I don’t know how to tracj it down and fix whatever client is trying this (shouldn’t be any).

2022-12-06 10:41:53: , not authorised.
2022-12-06 10:41:56: New connection from 172.30.32.1:46246 on port 1883.
error: received null username or password for unpwd check
2022-12-06 10:41:56: Client <unknown> disconnected, not authorised.
2022-12-06 10:42:00: New connection from 172.30.32.1:46256 on port 1883.
error: received null username or password for unpwd check

What can I do to fix this or find out where its coming from?

I suspect it is just supervisor checking to see if the broker is running. People have commented on it before. I don’t remember it being a failed login, but it might have been. I’ve just moved over to EMQX, which is a much more informative broker, so I can’t easily go back and check.

Yes, I’ve seen that, I should have mentioned I turned off watchdog.