So how do we know if something is a singularity? So it’s kind of an assumption that this happens every time by general relativity? And what part of it leads to that?

If I’m hearing right, yes some neutron stars could gain enough mass to become black holes, and we’re not sure yet if all black holes are singularities because not everything adds up right and a new rule could be discovered?

But the Swarzchild radius increases with mass linearly, while the radius of a circular body only increases with the cube root of mass, so could a neutron star get big enough to overcome the swarzchild radius without collapsing into a singularity? What is collapsing and when does it happen? How do we know if it’s a singularity?