It's the pin according to
@TeamZero, that the rollers roll against (same issue as with the Pentastar rollers actually...) that's improperly heat treated and eventually a ditch starts to form where the surface has been breached and this goes on for a while until eventually one of the rollers gets stuck in the ditch, then they all pile-up and the roller stops rolling on the camshaft, and that takes the lobe out. I believe both GM and Ford have the same problem (though GM has the added problem of their AFM lifters crapping the bed).
And yes, I think it emerged around the same time as VCT, I assume they must have changed lifter suppliers, because then we ended up with like 7 lifter revisions of them chasing the issue, where it is apparently "fixed" now, and the new lifters use much larger rollers (in the bearing, not the actual roller that rides the cam).