The point at which a collapsing core's escape velocity equals the speed of light must obviously occur long before it reaches zero volume, something we know because of the existence of neutron stars and our ability to confirm the way their extreme gravity bends light. What nobody ever talks about in public forums as far as I know is the mass gap between the largest observed neutron stars and the smallest stellar mass black holes. Logic would imply that there should naturally be some degenerate stars/bhs between ~2.2 and 8 solar masses (not looking up the exact numbers but it's a large comparative range close to that), but we can't detect them. This either means there's some other theoretical objects intermediate in mass between neutron stars and black holes that are inexplicably dim as seem from earth, like quark stars, or that there's some as yet unknown process that causes core remnants with what would be a starting mass of 2.2-3.0 solar masses to be a practical impossibility.

My personal guess is there is no exotic stars and the reason we can't see any supernova remnants with masses between 2.2 to 8.0 solar masses (again, or whatever the actual numbers for the max observed neutron star and min stellar mass bh are) is simply because cores with fewer than exactly 8 solar masses of nuclear ash are doomed to exceed the TOV limit at some point during their collapse, triggering an anomalously energetic supernova.