There are a lot of lines on this coin both sides. Are these radial flow lines? There is also what i believe is a grease-mediated smear in association with the flow lines, also both sides. On the reverse there is an anomaly on the steps. If radial flow lines then it would not interrupt the design elements. It doesn't appear to be plating blisters.
This is a pretty common look especially amongst the 90s LMCs. Hard to say if it's in the substrate or the plating but I lean towards the zinc. The reason for this is the direction of the grain; parallel side-to-side.