He made spectacularly poor choices as he often does - ignoring overlaps or cutbacks, shooting from impossible angles, lacking guile and composure and blindly taking shots while ignoring better placed teammates/passes. It was extremely frustrating to see him waste attack after attack.
All that said, I wouldn't write him off at all. With Zirkzee being slow, Bruno pulling the strings, and Dalot being poor - he was effectively our only outlet, and it was clear the pressure was weighing heavily on his mind - he probably blamed himself for the goal the whole game and was trying to correct his wrongs. The stupid yellow where he kicked it away was pure pressure. He's trying so hard to force things, expecting unrealistically high things of himself and spiralling into more frustration when things didn't work out. The ignoring of overlaps was because he was tunnel visioned in this pressure today and reverted back to baser instincts developed in a United career where he usually never has that option. There were previous games where he was more composed and less hot-headed - he can find those cutbacks and quick movements if he wants to. He has the skill to be a better team player (though the finishing still remains a question).
I think performances like these are growing pains, he needs Amorim to calm him down and coach him, and he needs to learn from such games. Trying so hard to force things is often counter-productive, the positive is that he never stopped trying, and he definitely didn't do a Rashford/Sancho and shirk away from responsibility or disappear in the game. If you saw him fail all the time, it was because he was trying all the time. I think there's still hope there. If he's in a mental space where he's confident and enjoying his game rather than succumbing to the pressure, we might see a much more exciting player (we have seen glimpses already).
Or maybe it falls apart instead, and he gets only worse from here if he refuses to change and loses faith in the process or starts blaming others. I don't envy Amorim's position right now - but good coaching might polish this frustrating raw talent into something very valuable.