Spaghettification is due to strong gradient in gravitational pulls between different parts of an object while approaching a black hole

Getting close to a black hole, gravitational pulls can vary significantly also in a matter of microscopic distances, and because of that the closest parts of the object get accelerated before the others so strongly, that the object breaks and gets "spaghettified", meaning "reduced to strings of atoms orbiting or falling into the black hole", instead of falling into it or orbiting it while maintaining its original shape

You can experience a similar event if you drop some ink close to a water vortex, you will notice it creating strings following the path described by the vortex itself, because part of the ink gets captured by the circulating waves simulating the gravitational pulls of the black hole (you can look for something about using fluid dynamics to simulate conditions close to black holes)