Update on my issue. 2015 Yukon Denali 6.2L first owner. The valve spring and lifter on cylinder 8 need to be replaced. Had a bent push rod and cam replaced.
Earlier this year I had the radiator, water pump, thermostat, and water bottle replaced. After that the AC condenser, rear lines and rear condenser.
Last year, the mag ride shocks replaced, steering column bearing twice, then eventually the steering column as a whole. None of this was covered my GM and the dealers (two of them) said sorry for your luck. That's just how these cars are... Never again.