My 2021 was in the transmission shop right next to yours this week! For inquiring minds, had first oil change at 2,500 km's, DCT fluid top up at 3,900 km's, and CEL came on at 4,200 km's for less than 24 hrs and about 30 km's of driving before going out. Brought it to dealer to check codes, and transmission codes came up (it was running perfectly fine). They spent a day reprogramming, testing, wait for it to cool down, and reprogramming and I'm hopefully picking it up today.
True test will be Mosport on Monday. Fingers crossed.
Picked it up last night. All seems well. Here is the code and the work performed according to GM service bulletin. Seems like a lot of software and solenoid cleaning!
I had solenoids flushed on two occasions and codes still got thrown. They are now going to replace the filters and valve body module. Be 2-4 weeks for all the parts to arrive so they told me to take the car home and park it till the parts come in. Better than leaving it outside at the dealership.