On FP OS 19.02 and have recently been experiencing a battery drain when the WiFi is on but not connected. I think I’ve seen this reported on the forums before.
For this reason, I turn the WiFi off when I’m out of range (walking, commuting etc.). I’ve noticed however that the WiFi likes turning itself back on after a few hours. Not sure why. Location services is off and WiFi scanning is off.
I was going to report it as a bug but just wanted to check this wasn’t a more general Android issue. My online searches weren’t very successful.