Can’t see your feet. I suspect the bar isn’t over midfoot and you might need to rock back just to put the balance back where it belongs. Some reps look forward, some end up with you on your heels. I’m thinking maybe bar placement is too close to your shins. Can’t see for sure from the angle of the videos that we don’t want. Read the sticky.
Back looks fine. You’re just underweight. I don’t know what you cut from.
Also, fire your barber.