Normally drop is provided in slabs to reduce the amount of negative reinforcement in slabs over columns, or to reduce reduce overall thickness of the slab. In such a case, the drop must be centered on the column, as per relevant code provisions.
The slab position, visible in your attached images, reflects the situation where two nearby slabs exist in such a way that one slab is at a slightly higher level than the other. Moreover, lower slab is a cantilever, acting as a support for the free edge of of upper slab. In such a case, drop may be at any location, provided it is properly designed structurally.
Regards.