The fact that she could position the mask at the exact spot the predator would be standing... a bit of an overreach.
On board with everything else until this part. Why not just have her wear it and look at the predator -- that would have been more believable.
That was probably the only part I could get on board with compared to everything that came before it.
Her beating up three full-grown after she brushed off that bear trap attack was when I "noped" out.
After the Predator cut off his own arm, and she out-fought him hand-to-hand and dragged him to the ground with the rope-axe, I didn't really care what happened after that.
Ironically, the Predator shooting himself in the head with his own mask was a mercy kill at that point. At least he was put out of his misery from being further humiliated by a teenage girl.