If you are referring to the recent news regarding quality issues with Olympic medals, investigations have been launched into reports of medals cracking and chipping.
Nature of Damage: Medals frequently fell off their lanyards, fell in the snow, and broke in two. medal crack
Stress Corrosion Cracking (SCC): This is the most common culprit for "medal crack." It occurs when a susceptible metal (like brass or bronze) is exposed to a corrosive environment while under tensile stress. Over time, microscopic fissures turn into visible cracks. If you are referring to the recent news
The Origins of Medal Crack