There is no such thing as "too small to form a black hole". There is no minimum mass for a black hole.
There is a maximum mass for white dwarfs and neutron stars; for white dwarfs, it's about 1.4 solar masses, and for neutron stars, it's somewhere between about 1.5 and 3 solar masses. We can't pin it down for neutron stars any closer because we have a poor understanding of the equation of state of matter in the relevant density and pressure regime.
I don't know if quark-gluon plasma is even stable in the relevant density and pressure regime, but if it is, I suppose there could be a maximum mass for a quark-gluon plasma "star" that was somewhat larger than the maximum mass for a neutron star, so there would be a range of masses where gravitational collapse could stop at a quark-gluon plasma star instead of a neutron star, and would not go on to form a black hole.
There is a maximum mass for white dwarfs and neutron stars; for white dwarfs, it's about 1.4 solar masses, and for neutron stars, it's somewhere between about 1.5 and 3 solar masses. We can't pin it down for neutron stars any closer because we have a poor understanding of the equation of state of matter in the relevant density and pressure regime.
I don't know if quark-gluon plasma is even stable in the relevant density and pressure regime, but if it is, I suppose there could be a maximum mass for a quark-gluon plasma "star" that was somewhat larger than the maximum mass for a neutron star, so there would be a range of masses where gravitational collapse could stop at a quark-gluon plasma star instead of a neutron star, and would not go on to form a black hole.