It's not the clutch . It slaps against b-tension adjuster . I modify the mounting bolt to have more resistance to make chain slap at least on par with cable versions
Something along these lines?
Homemade "Hall lock" for Sram & Shimano
A brilliant solution on a homemade "Hall Lock" for Sram and Shiamno derailleurs from my buddy Collin Timmermans! https://www.youtube.com/watch?v=IChC4h8WDkA
www.vitalmtb.com
I've tried similar on a non-AXS derailleur and it did have a moderate effect.