A bunch of people are weaker on rack pulls than from the floor; I mean if the pull starts just below the knee, which is the usual sticking point. I did a ton of racks, all heights, even just the last millimeters to see how much I could make leave the pins without straps LOL.
Tip on rack pulls: if the load is close to limit weight it might feel like forever before the weight starts moving, don't give up, give it a while just pulling even harder, it feels like seconds but might just be fractions. The subsequent reps are often easier.
Also
Don't be an asshole and bend nice bars on the rack

We used to set up in the rack then build up boxes on the sides to meet the plates.