XC70 2006 model noise metallic tapping noise while driving- automatic 2.4L geartronic

I have just bought a 2006 XC70

it’s making an intermittent noise, usually when driving at lower speeds (40-80 kph) having been driven at higher motorway speeds for period of time

noise occurs when coming off accelerator

appears to be coming from underbody of car and frequency of tapping related to speed - it disappears around 100 kph

noise is attached as movie file

anyone experience this or know what it could be

unfortunately the noise is intermittent and did it occur when garage took it out to assess

 

Link to video recording of sound