Do you move your (lower) back back and forth during the exercise?
I find mixed recommendations online. so far, I think it is better to keep the lower back stiff and focus on arms, shoulders and upper back. Also, you don’t move the back when doing barbell rows which is the same movement.
For example, jeff nippard moves his back at 6:00 min in this video https://www.youtube.com/watch?v=PAXkl-AdJFg not as strong as others do, but still.
Here, they keep the back perfectly straight https://www.muscleandstrength.com/exercises/seated-row.html
In my gym many people (all that I witness) move their back.
I don’t think it matters much as long as you aren’t pulling hard with your lower back and it taking over for your upper back. If the movement is slow and smooth, your upper back/arms should be the limiting factor and feel it.
That being said, I do prefer to keep my back as still as possible.