What I mean by that is, if you're wondering why Sally's squat form looks different than yours, well, it's probably because it is!
We're all built differently.
When it comes to squatting, someone who has longer femurs may have a bit of a folding squat than someone that doesn't. Someone that doesn't have [relatively] long femurs may have a more upright chest in the bottom of a squat.
Now this isn't to say, just accept it because this is how you are! No. We strive to improve 'round here. We just want to build a safe and efficient body, based off of YOUR body, not someone else's. Plus, there are many other factors that can play into how you squat (feet, ankles, hips, knees, back, chest, core engagement, etc.)
A couple of the most common occurrences are:
Test this by getting into a half kneeling position with your big toe planted 5" away from the wall. Can you reach your knee to the wall without your heel leaving the ground? If yes, great! If no, that's okay! If performing a full depth squat is a goal of yours, I'd suggest incorporating some ankle mobility drills into your routine.
It's common to have tight hips due to the sitting you do for work + a [likely] high stress environment. To increase hip mobility, I'd suggest adding in a couple hip mobility drills to your routine, especially on your squat days. This could include the 90-90 stretch and a kettlebell hip opener. (I didn't find any great YouTube videos to demo this, but it's in the KATHLETICS app Library! 😉) The kettlebell hip opener is essentially a goblet squat where you hang out at the bottom of the squat for a duration of time, use your elbows to pry your knees out and shift your weight slowly from side to side.
Give these a go and see how you improve over time!