New 5rm of 160kg/352lbs just looking to see if form looks okay
It seems that you are not correctly engaging your hips which causes your lower back to round forward. You could try standing just a bit closer to the bar and try to bring your hips down and chest up just prior to liftoff. This should help you keep your lower back in a more beneficial position as well.
Okay thanks will try that out, do you think the rounding is excessive?
Overextending your lower back in either direction is a habit you should aim to eliminate immediately. Try to maintain your natural spine position in your lower back and only allow rounding of your upper back if even that. It's a technique not suitable for everyone and it definitely shouldn't show this early.
I think the problem was what you said with the bar not being close enough to my shins normally I place it at about 1 inch away but today I tried it a little further out 3-4 inches away from shins do you think that could have been the cause?
3-4 inches away from your shins is way too far. You should be positioned in a way that puts the middle of your feet straight under the bar.