Sound volume changes randomly with Bluetooth headphones

Sound volume is quite unstable with Bluetooth headphones, as sound keeps getting cut off plenty of times. I don’t know what is the problem. It’s not only with one particular brand like Sony or Audio Technica. EVERY bluetooth earphone and headphone are presenting the same problem.

I need to shut off FXSound in order for the audio bluetooth to get back to normal, but then the audio becomes of lower volume instead.