An update for anyone interested.
I had some weird behaviour from my “smart extractor”
Investigating showed some errors in the ESPHome logs, looked like the Temperature and humidity sensor died.
So I replaced it, and still had the same behaviour, seems my Sonoff TH16 failed.
Connected the original sensor to a D1 mini and all is well again in the land of “smart extractor”
Now I have a spare sensor to use for something else.