@Emiel1,
So the last time this issue occurred, the major cause was "instant book" being activated (we NEVER allow Instant Book) and us recieving a booking while we were out of town. We called AirBnB, they admitted that there was a glitch in their system while I was on the phone with their support person.
24 hours later, we get a booking during our high season (May 1 - Oct 1) here, at >50% off our standard high season rate. We had not even logged into our account since speaking with AirBnB, and the rest of 2018 was set to 'Smart Pricing', which we do NOT use ever.
No one else has access to the account, we have asked AirBnB to confirm the IP addresses of the most recent logins, and they have refused our repeated requests.
We have never had any of these types of issues before on other platforms, it only seems to be with AirBNB.