A Q Star, also a grey hole, is a hypothetical neutron star. It contains a strange matter. It would have a gravitational pull so strong that some light, but not all photons can escape.

https://en.wikipedia.org/wiki/Q_star#:~:text=A%20Q%2Dstar%2C%20also%20known,not%20all%20photons%2C%20can%20escape.