South Africa 1990 2Cent - Off-Colour

What happened to this South AfricaN 1990 2c.
It is way off colour compared to other 2c pieces.

Any ideas?
All three coins came from a junk lot I got from friends / family

Weight 4,18g, slightly less that normal 2c.
Diameter 20,61 mm
Magnetic

5 cents. I think the 1990 just has more wear that removed the bronze plating exposing the steel underneath.

My thoughts as well, just wanted to get confirmation.
Thank you