NHTSA Complaint #11719705 — 2020 GMC YUKON XL

My 2020 GMC Yukon XL Denali 6.2L with 59,000 miles developed a ticking noise and slight power loss diagnosed by three different garages as a "collapsed lifter" on #4 cylinder. It's one of the AFM/DoD cylinders that shuts down to save fuel. $8,000 repair estimate, or $12,000 if the failed lifter damaged the camshaft. All three garages said "we see a lot of these." Internet forums are loaded with lifter problems on this engine: specifically AFM/DoD lifters. Safety is not affected. Noise/diagnosis reproduced by three independent garages. Has not been inspected by mfg, police, or insurance rep. No warning lamps or messages, no ODB2 "codes" found by garages. Seven months ago the water pump exploded on Interstate 70, putting us at serious risk. Now this lifter trouble at 59,000 miles. Both should have been covered by the 60,000 mile powertrain warranty, but I'm beyond the 5-year limit.