you pretty much only see jello in the dashcams that are on a stalk as it is often not rigid enough, and then the camera start to oscillate at a different rate than the car.
You might already have this in the mirror of the car, i know in my little Suzuki car at low RPM the mirror shake, but once i get up to a little speed it stop.
The wedge cameras most often stay in place if you have cleaned the glass good before install, actually if the come loose most often its the bond between the sticky pad and the plastic mount, in that case i have just put more glue on those surfaces and stuck them back together.
But this have only happened for me 1 time over the past god know how many dashcams.
Also aside for the risk of jello, the cameras on a stalk are also less stealthy, as it is offset from the window glass quite a bit. only plus is as they are on a stalk you can reach over and turn it, but this in turn will be seen by people and they will be suspicious.
Some of the Uber style cameras do have a cabin lens you can turn to face either door window, but again reaching over to do that will make people see, and these cameras are already not that stealthy.
The viofo A129 with the IR cabin camera on a wire will be ideal, i would put the cabin camera on my mirror stalk ( even if it shake at some low RPM higher than idle ) or i would out the camera on top of the windscreen near the R side A pillar and then aimed over towards me in my L hand drive car, this way it have the cabin in view and any person that might turn up at the driver side window, and police always do that here unless you are pulled over on a motorway.
you can also see jello a little in the start of my video from the B2W uber camera i am testing, it have come loose in the mount again, and then even on a fairly good paved Danish road i get jello.
When the mount are nice and tight this will not happen.