Deformities
Look at the inconsistencies on the edges. Why are they there? Can you think of a reason why someone has recently, intentionally, damaged the ingots?
One simple explanation could be that the casting molds were uneven. Another explanation would be: when metals are cast, sometimes gasses become trapped within the metal. While the metal is cooling, these gasses attempt to escape, which results in tiny cavities in the final product. The fact that Bronze Age ingots had many of such holes would mean that they were rather easy to break. Another often occurring error is caused by shrinkage. After the metal is cast, it cools down, causing it to shrink and sometimes leave behind cavities.
Regarding the recent damage: scientists have removed a small (1 cm by 6.6 cm by 4.5 cm) triangle with a hacksaw from the backside of these ingots. They used it as a sample for studying the composition of the ingots.
Time to go to the signs on the ingots; the writing.