There are potential reasons why the mentioned flange might be oversized, I'm having a hard time imagining how they tested frequency resonance and decided to just fix it by leaving a little extra material near where the welds go though. Or likewise deciding that the extra material in the weld zone increases safety by some margin. Those possibilities seem like they'd require and extremely nuanced and subtle understanding of the car and the whole process, It's possible, I guess. What's far more likely is that they just haven't done a round of cost reduction as they're just struggling to get the initial manufacturing done for the pre-orders.