Squat form check and hopefully improvement!

My squat today

and 3 weeks ago for comparison:

I’ve gone back to basics, maybe overdone the prowler for a couple of weeks … My 1rm estimate has gone down but I’m happy with improved bar path and less fatigue.

Any form advice would be appreciated.

The camera angle makes it difficult, but it looks like you are losing tightness in your upper body once you hit the bottom of the squat. It kinda looks like you round your upper back for just a few secs.