BBC said that her bag was Togo. Do you think it's the type of leather or the size of the bag? I have mai tai inserts for my Togo b35, k35, k32 and k32 sellier and I haven't noticed this at all.
I realized it wasn't her swift bag after I posted but I still think the Mai Tai measurement is off, I gave it to a friend and it was too big for her Box B30. I have one in my B35 Barenia but that was a preloved, slouchy bag already so I didn't notice the issue but I did on this latest purchase. The Mai Tai I reviewed recently was her new design but I had the same experience with my K35 insert in the old design. I think they're just a bit too long for the bag and if the bag has slouch, it pushes the batwings out if you know what I mean. I do think the new design (and the old) are nicely made and a fair price, I think it's about matching the right insert for each bag though.
Also, as H bags are handmade I'm sure the measurements vary. There's a few threads where bags differ up to 2cm so no insert is going to be perfect for every single bag.