The most common reason a vehicle squeaks when driving over bumps is due to a bad suspension system.
The rubber bushings that are made into the suspension can start to dry out and crack which can cause the squeaking sound when you drive over the bump.
The suspension of your car helps to smooth out the ride of your vehicle when driving over bumps and down the road.
So when the bushings on the suspension system are bad the car can squeak.
You can also push down on the bumper of the car in the front and back and listen to where the squeak is coming from and it does squeak when bouncing the car up and down then suspension is the problem.
You'll usually need new shocks or bushings or a new suspension system to fix the squeak.
There's no harm though in driving with squeaking suspension so it's not an immediate fix that needs done if you cannot afford it.
The squeaking can be annoying when driving over bumps but it's not dangerous to drive with squeaky suspension.