Hi,
Yes, the boundaries of every district of West Bengal were updated a couple of months ago to the ones provided by SOI for free usage through their “Onlinemaps” portal. Kolkata in itself is a district (admin_level=5). Now if the district boundary was previously from the KMC data, that would’ve certainly been incorrect, though we can add this back as a Municipal Corporation/Muncipal Boundary (admin_level=8). The boundary for KMA/Greater Kolkata could also be added separately as a boundary with admin_level=7.
Hope this helps!