It’s almost definitely IWE related. About three years ago, my 2018 would do it every so often on slight inclines when cruising under light throttle. It did it three times on the way to drop it off at the dealership and then wouldn’t do it for them. I even went back by and drove it around for two hours myself and couldn’t get it to do it. Finally they brought in their tech who does all their front axle work in to talk to me, and he described the exact conditions of when it would do it. He went to the parts department and got a check valve that had short pieces of vacuum hose on both sides and replaced it in the parking lot. It was on the drivers side near the firewall under the hood if I remember correctly. It took him about 5 min to replace it, and it’s never done it again in 3 years and 25k miles.
