Part of the rim should be missing with a clip. This looks like some form of corrosion. But wait for some others to chime in.
No.. It is not an Incomplete Planchet. Looks like damage to the clad in that area. Edit.. I had a brain fart. Peace Dollar not clad
a 1924 Peace Dollar is not clad. This is a fake coin. Why someone would want to fake a common date is beyond me. An MS state 1924-P can be had for around $50 to $75. A 1924-S is worth quite a bit more in mint state, though.
I would need to see both sides and the edge of the coin to be more certain but I believe this to be a fake coin. It appears that the metal has rusted and it was plated.