I notice is a little spinal reversal near the bottom of the squat . It doesn’t look too bad in the first video but it’s more noticeable in the last two.
It looks like you’re going through the bracing sequence but still may be starting out a little overextended. Keep working on t spine extension.
This video is a little long but well worth the watch.
The usual the culprits are usually hip and ankle. I’m going to guess hip in this case. Really focus on the stable hips (knees out). Don’t focus so much on going ass to grass deep but get your hips just below parallel or until you start to loose position that’s all the further you really need to go .
A shot from the front might be helpful to look for loss of knee position. But it looks okay from the side.