Sounds like the spontaneous mystery override of your own settings. Maybe airbnb is doing it to boost their number of bookings for their statistics and even if you get them canceled they can count them.
I’ve had a lot of spontaneous loss of my event rates over years. And spontaneous re-activation of unlisted listings, as if you only snoozed temporarily when you definitely unlisted.
The closest thing I’ve had to what you’re seeing is spontaneous loss of my no check in/out on Dec 25th or other special settings.
Obviously you’re using instant book right? Seems like instant book listings are the ones that get the most “errors” with glitches of this nature.
I would do one or both of these things:
1. Put in first line “one night stays are not allowed” and see if people at least start messaging you first before trying to book 1 night
2. take it off instant book