The short answer is: better ankle mobility.
I highly recommend to get some video footage of your training sessions with your phone, when you have a chance. Not for Instagram, but to help you picture your movement while you are performing it.
It's actually how pro athletes train, with more cameras. Attention to details will increase your results. It is simple and does wonders to your workouts and progress over time.
You can take a few 10-15 sec highlight snippets, of any movement, to check your form, and see where you can make progress, then adjust your form next time you train.
This will make your legs more mobile and improve your squat!
Have a good squat session later!