Okay, I think I've gotten my shudder bucking issue fixed. A RECENT TSB # 22-NA-211 WAS ISSUED A FEW MONTHS AGO ON JAN.19TH 2023 FOR THIS PROBLEM. Seems Shudder Bucking, it is also caused by a leak of fluid in the front lower control arms of the front end suspension on the 2016 thru 2020 Envisions. My local Buick Dealer replaced the damaged & worn parts yesterday and we went for a 1/2 hour long test drive over the bumpiest roads filled with potholes and the most imperfections to really put the car through it's paces and it performed and rode like when it was new. My fingers are staying crossed until I get this "non bucking presence driving results" long term. SEE ATTACHED TSB INFO.
GOOD LUCK EVERYONE!