Foggy when doing an exercise? Felt odd today

I was doing a leg press. I did add more weight than I have in the past but not a ton more. Here’s the thing. I could do the exercise at the weight. I felt fine doing it from a leg strength perspective. But I did feel weird in a hard to describe way. No pain or discomfort but definitely felt like a bodily response. Like there was a perception of weight on my shoulders even though I did t actually feel anything. After I released the third set I briefly got foggy which is worrying.

But I’m not sure what caused it. The weight should be fine. I actually was regretting not doing more reps.