Your first rep has a good bit of tail tuck in it in the very bottom. Where your tail bone tucks underneath you. The rest of the reps either didn't have it or had it just a little. So I think you have the mobility and the strength. I think just focusing on your form and making sure you arch hard in that position will take care of that.
The bar goes straight up and down over your midfoot so that tells me the bar isn't getting in front of or behind you.
Some people can get away with tail tuck and others can't. If you feel undue back strain then definitely focus on improving it. If you want a specialized exercise to help with it, I'd go with paused squats. Just be sure your actively resisting the weight in the pause and not just passively hanging out there.
Personally, I just think practice with regular squats will do since it's not god awful terrible.