The 1992 Cent is a Copper Plated Zinc Cent. Plated Cents tend to have problems. Looks like you have a plating issue. As mentioned Post Mint Damage.
Mint marks are not placed onto the surface like decorations are placed onto a cake. They are part of the design on the Die. Could also of been a slight Debris filled Die which lead to a strike such as yours. Heh heh