Tight hips are the biggest mobility issue that I see as a trainer, this is because a large amount of people spend the majority of their day in the seated position. The longer we sit the more likely the muscles in our hips are to tighten. Are you able to go to full depth (ass to grass) on your squats? If not, theres a strong possibility that it’s your hips. Try this stretch out before your next squat day and let me know how you feel after! Disclaimer: Don’t make eye contact while doing this stretch, it’s awkward.