You have felt this one before.
The bar is loaded to a number you have already hit. You brace, you sit into it, and out of the bottom it slows. You grind it, you rack it, you call it a bad day. Then it happens again the week after.
So you change something. More sets, fewer sets, a rep scheme somebody posted. Two good sessions, then the same weight stops you in the same place.
You cannot tell if it is your form, your programming, or you. That doubt is the problem. Not the weight.