About a month ago I got the normal 7500 mile oil change/tire rotation for my 2015 5.3l V8 GMC Sierra 1500 (79k miles). Later that afternoon after running around town for a couple hours, I end up clearing out the main drag in town with billowing white smoke out the exhaust. Got home and checked stick, was about 5-6" above the max fill line. Dealer owned up, towed truck back, and essentially made it right. Didn't have any issues immediately after that. Made sure to have all of this pretty well documented for if a future problem arose.

Fast forward to Wednesday and I'm driving to work, get on the gas as I hit the on-ramp and immediately have a bad shudder and a few popping noises from the engine at ~45 mph. Stabilitrak light comes on and check engine light starts flashing. Has jumpy shift when slowing down for a stop/turn, and idled rough. Ran codes and got a Cylinder 6 misfire pretty much constantly. Definitely had a bad "tick" sounds too which seemed similar to the AFM thread from a few days ago. Took it over to a reputable local shop and diagnosis isn't good: Confirmed the misfire, and a bad lifter, along with metal shavings and fouling in oil system. Probably won't be able to hear anything form the dealership shop until in the morning.

Powertrain warranty is still good, but is this something that would be covered under that? And if not do I have a legit case of dealer oil change overfill causing these problems?

What does "essentially made it right" mean?

Towed truck, drained and changed oil again all on their dime. Checked for any obvious damage and ran codes with no issues.

I don't see how overfilling the oil would cause this failure but if it's under Powertrain, it's irrelevant