Okay. Thank you all so much.
Could the hyper extension be from not bracing the core as hard? I feel like I really try to tighten my lats before the actual squat. Or could it just be the angle of my spine?
The hyper-extending could be from you exaggerating sitting back and "poking" your ass back to much.
You want to brace, then draw the bar down into your traps, and after break at the hips to begin the movement. I think some people over arch their lower back from thinking "chest up" and "sit back" so they puff their chest up/high which makes it easier for them to over arch their lower back.
Everyone has their own ques they go through when they're setting up for a squat or any lift. You have to find what works for you. I think and this may not work for anyone else... I unrack the bar, take 2 small steps to get set, then I brace (think someone's gonna punch me), after I draw the bar down into my rear delts, and finally I think spread the floor as I descend. It's a lot but truthfully most of it falls in line if you're properly set up to begin the lift. So for me it's... Brace, draw down, and spread the floor.