I have a 2020 Sierra Denali 1500 with the L87. Bent a pushrod into an S Curve shape at 8,000 miles on April 18. Happened on a road trip when restarted after fueling. Repair requires replacing a high pressure fuel line, which is on backorder. Dealer technician is outstanding and he indicated this is a common problem. Took it to the dealer on April 19 - now might not be repaired until next week.
This is my 3rd 6.2L L87 (previously owned a 2017 & 2018). This is the first engine issue I have experienced.