I think you're talking about concerns that a quark gluon plasma could recreate the conditions near the big bang to the extent of producing a primordial black hole which would then proceed to swallow the earth whole.

There is no experimental evidence of primordial black holes and the theoretical evidence is tenuous (mostly based on "semiclassical" reasoning). In addition, a quark-gluon plasma has already been produced in heavy ion collisions in other experimental facilities and we're still here.

We have met the enemy, and he is us — Pogo