In that expression CL is the lift coefficient and AR is the wing aspect ratio. I hope we can agree that if airspeed is increased the lift coefficient is reduced, so that downwash, to my definition, would be decreased
Cl does decrease, but total lift force is constant regardless of airspeed (assuming level flight)
This means that to maintain lift at higher airspeeds (lower aoa and Cl), more air mass gets accelerated faster (vertically) giving
an increased downforce on the tail. F=m*a