Yes, that is normal for Papain (natural Papaya-based enzymatic meat tenderizer). Papain is an enzyme from papaya, and raw papain powder can have a naturally strong, unpleasant aroma. People may read it as sulfurous, fermented, rotten-egg, fishy, or overripe fruit. That smell by itself is not automatically a sign that the papain is spoiled.
What matters is the condition of the powder. It should be dry and free-flowing, without damp clumps, visible mold, unusual discoloration, Papain is moisture-sensitive, so keep it tightly closed in a cool, dry place.
For cooking, use it sparingly as per the instructions on the tin. The flavor does not carry over in meat tenderizing.
The aroma is strongest in the fresh raw powder and may be noticeable if too much stays in a finished blend or marinade.