I don0t understand if it could be related to a problem of signal strength…anyone have some ideas?
I have several MiFlora in a greenhouse, all connected to hassio via ESPHome.
This is not probably going to solve your issue but I would advise you to connect your MiFlora the same way. It has the nice benefit of exposing a sensor with the rssi - the signal strenght. Bonus point: you can have your MiFlora far from the hass.io server.
Get yourself a pi zero and run plantgateway on it, then get the data in home assistant via mqtt.
-79 is not exactly a good signal strength and this value may also be changing depending on environmental factors…