Transmission hesitates and jerks, primarily with take off from a complete stop but also going down the road. When we first bought this car and had the same problem, the dealer updated the software and flush the radiator. That seemed to work until now, with 15700 miles on it.
The 2018 Enclave had a 6yr./70k powertrain warranty, transferable to the second owner. It sounds like you bought yours new anyway. Keep after Buick until it’s fixed. If necessary there should be a number for corporate in your Owner’s Manual.