I'm also using openhab mqtt. It ist not a real problem, as they reconnect as soon as WiFi is back up again. However I don't like them to appear in the list of available APs during the downtime of WiFi. (my neighbours do not need to know all my ESPs)

I recently noticed that when WiFi is switched off or down (during router upgrade or for maintenance) all previously connected ESPs appear as access points on channel 1 (and can be connected provided you know the WPA AP Mode Key).
Is that a bug or a feature? How can that be disabled?