We have no idea how many have been destroyed.
My guess is rather few, because there is a lot of shooting being done and there have been under 500 155mm guns delivered to Ukraine (from all sources, not just the US). They are using them very heavily. There are only so many shots you can fire before the piece needs a rebuild.
They are shooting ammo off at a rate the whole US Army did not plan for its 2000 pieces.
Yep, worn out unreliable and inaccurate. Need DPICM. Excuse/replacement for maneuver. IOW done.