Rax Quintanilla,
No, my Bluetooth audio volume playing to my Sonos Move Speaker is the same (loudness) volume as when I am AirPlaying the exact same track to the device. I chose approx 50% volume in the iOS AirPlay/Bluetooth device selector… it’s also the same volume (or thereabouts) when playing the same song over WiFi, via the Sonos App (Room volume control set at approx.50%) … at least not that anyone would ever say there is a huge difference between each of the different playing volume levels.
My Bluetooth and AirPlay source for the test was the Apple iOS Music App via the Apple iPad and the Wifi test was done using the same device Sonos controller software.