Is this a lack of lower back strength?

This was a 1rm attempt at 150kg. I hit 145kg without issues of back rounding. This may seem like an obvious question to ask, but I have only been deadlifting for 6 weeks, so my form has lots of room to improve.

I would have thought the form in the video is an issue of lower back strength, but is there something else about my form that could be putting my back in a disadvantageous position?

Any exercise suggestions would be appreciated also! Thanks!