The body is the best doctor.  When I put my head near my WiFi router, I get a headache.  That tells me there's something harmful coming from there
I tried Bluetooth.  Same.  Within 10 minutes, headache so I stuck with my wired headphones. I have literally not seen one person on the street use wired headphones for years.  The ignorance/apathy is astounding.  The dangers are not even being hidden any more.  1 simple Google search is all it takes.
What's even worse is you see players pre match using Bluetooth all the time ( very prominent in EPL ) and nobody at the club tells them not to.  That can't be good preparation and will almost certainly mean lower performance.  Glad our players don't seem to do that.