I’m actually the guy that posted months ago first about this issue and am a still fighting Toyota about it. I got my pro back in February and lived in South Dakota. It was actually a blizzard the weekend I got it and with neg 0 temps regular within two or so months heard it. It actually started after I was off roading and was fine for the first two months. It’s sounds more like a blown sway bar bushing but you can actually feel the floor board on the passenger side move. It was so bad passengers would hear it on the bumps from ice on the road and ask what’s wrong with the rig. I started a case with Toyota and am pretty sure I drove them crazy calling every week to find out when they would fix it. At the time only three reported cases and all from the same regional tech. I also called Fox and talked to them about it and they were not happy Toyota blames the shock. I’ve had many stories told to me from Toyota techs that it’s hard to believe any they say. They even told me that Toyota rushes the shock out for 19 and used the Tacoma’s settings that clearly isn’t correct for the 4runner and they just need to figure out the tuning.
I’m moved now to Mo and let the dealer here look at it in hopes of fixing it. They tried to order a new shock and Toyota blocked it saying it’s a know issue with the Pro and will not replace them. I’m sorry but my alignment goes off very often and has to be reset, any low speed bump is a hollow thump at any temp so the low temp only makes it worse and noticeable. You can feel it on the floorboards at lower temps. I even considered trading it on a 2020 today while there and of course they want to give a low ball for them as expected. This isn’t my first 4runner or off road truck, but Toyota messed it up and clearly doesn’t care about making it right.

To the guy that said tune the taboo up btw, the thing was so loud you’d blow your speaker. Also at highway speeds the truck was becoming unstable. This isn’t a flaw. It’s a f..k up. You don’t drop that kind of coin to put up with shot Warrenty and customer service.