Had this done with my 2019…
Had this done with my 2019 Silverado LT about 2 years ago when it had around 35k. The dealer told me the early built trucks got a certain trans fluid and gm found it to be faulty, so mid production they switched to another trans fluid. So mine was all covered under the factory warranty and they did the flush and refill with the newer fluid. I'm at around 62k miles now and so far no issues.