The gold warning sticker came in affect from NGH 93 iirc. Most carts after that had it.
Some of the last releases, SVC, SSV/S, Sengoku 3, Metal Slug 4/5, Matrimelee didn't have it.
Japanese Metal Slug 3 1st run has it but 2nd run doesn't. They do have difference in the last page of the manual too.I had 3 different metal slug 3 carts that one had it and the others did not. All 3 had of labels.
1996, not 93.