It’s impossible to tell anything from the picture. If that is a rim joist which is out in space, then it is not a structural member, and serves primarily as trim, and to keep the ends of the joists from rotating. If it is a rim joist at the end of a cantilever, the uplift, if any, is at the far other end of the joist, so there is no reason for the joist hangers to be upside down. In fact, there is no real reason for joist hangers at all, since the rim joist isn’t structural.
Depending on the loads and the relationship of main span to cantilever, the uplift on the other end may be very small, and easily carried by the nails in the joist hangers. If the cantilever is large and the main span is small, the uplift could be considerable, and as has been stated, the connections then should be specifically designed to resist the uplift.