Ya gotta wonder ifin the Plumber that done the job from the outset used “thin wall” copper pipe which would suffer errosion at a far hreater rate than standard wall copper pipe.
We had a run on some copper pipe down here about 10 years ago that for no aparant reason developed pin hole leaks, however we put it down to our hard abrasive water we have here. Perhaps we were a little hasty in that asumption and maybe it really was a fault batch of copper pipe.
It may even be a breakdown due to electrolosis with an electrical current passing through the copper to earth.
Would be interested in what others may think.