I do not think this is a super wide spread issue, It was a huge issue for a number of trucks in 2019 from what i read. at that time and the pandemic everyone who bought a truck was on the internet home off work or working from home.
There were many trucks that had lifter failures at that time. GM issued a build date with the failed parts. So everyone was searching the net and this SITE is always at the top of the search. Look up how many of these T1 Trucks have been sold. then browse or search for identified trucks with Lifter repairs. you will find its not that great of a problem. My guess is the ones we are seeing now are just failures in the normal range . Every mechanical device manufactured will have a Product fail rate .
if you could do a internet search on a brand new computer tied to a brand new ip address from a brand new internet connection not associated to any home or person and then search 2019 2020 2021 GM or Chevy truck issues. You will probably find people complaining about what Consumer reports is complaining about the Interior of the trucks. because they do not have rain sensing wipers and some of the other gimmicks that apparently are now required for even Work Trucks.
The Issues thou are Annoying and i would be MAD as well if it were my Truck. This is not a Wide spread issue. Thou it is a issue.
Good Luck on getting it fixed .. but i do believe you may need to switch dealerships . If a service provide does now a issue from the very first second you contact them you do not need to let them touch the product. Listen to there voice . if they lean to we we will see what is wrong with YOUR TRUCK.. . They say get it to us so we can Fix this. We will take care of it..
Those last two make all the difference .