@Hugo127 The last iPhone updates have made notifications less reliable. Sometimes I don't even get notifications for a text message for any number that I don't use a custom tone. AirBNB messages are also a bit random, though they have become more consistent in the past day.
You have no doubt checked the SETTINGS --. AirBNB, but you should also look in the AirBNB app. There is a separate SETTINGS option under profile that must be turned on [and for some reason was turned off during the last update.]
Not sure that this is clear, and I have to go wash that laundry again!