Hello and welcome to JustAnswer!
It could potentially be an issue with a height sensor, the control module or a wiring issue between the module and shock, but it's likely the shock itself.
What you can quickly do to rule out everything else would be unplug the shock. The electrical connector on the top of the shock can be disconnected from inside the trunk and this will take all electrical control away from it. Just in case, you might put a floor jack underneath to take the weight if the shock does suddenly release and drop.
If unplugging it has no affect on it then the problem is in the shock and It will need to be replaced.