I have a 2017 Buick Envsion and am experiencing the same issue you describe- slowing for a light, then accelerating causes shuddering, low speed hard shifting, lurching, grinding through shifts. Occurs each and every time I drive. I am at 8 months, 7000m and 4 service visits in which the service manager rode with me and said, “Yep, I am afraid that is just normal with these cars. There is no fix available from Buick for that”. A retired GMC engineer rode with me and describes the car will use “adaptive learning” to the way I drive. Said I might try driving it “harder”, but has been a known problem with many GM cars in recent models. However, this is a low speed issue and happens at speeds of 18, 24, 32, 44 mph and as such I cannot drive harder in city traffic! I do not find anything “normal” about this shuddering and lurching through gears and am insulted to suggest it is caused by the way I drive. I have had many other cars, including 3 Buicks- and not 1 has driven like this. I am angry and heartsick every time I drive OR ride in this car and I can't believe I spent a years salary on this lemon!