You didn’t include a photo or description of the color change, but the yellowing, cloudiness, or change in hue of ice cubes after such a long time is most often caused by a few factors:

Absorption of odors and gases: Ice in the freezer acts like a sponge. Even through sealed packaging or bags, it can eventually absorb odors and volatile substances from other foods (e.g., vegetables, meat, fish), which can alter its color and taste.
Oxidation and mineral deposits: If the water had a high mineral content (iron, manganese, calcium), the gradual evaporation of a microscopic layer of ice (sublimation) caused the minerals on the surface to concentrate and oxidize, often creating a yellowish or brownish tint.

Leaching from plastic/packaging: If the ice was stored in cheap plastic bags or silicone molds, the materials might have reacted over time, leaching dyes or chemicals into the ice.

Sublimation (freezer burn): After a year, ice loses moisture and shrinks, developing an opaque, matte, or chalky-grey layer.
Recommendation: Do not use these ice cubes in drinks. The altered color and long storage time mean the ice will likely have an unpleasant taste and may contain concentrated impurities. Discard the old ice, clean the mold, and fill it with fresh water.

(If you wish, describe exactly what color the ice turned or what was next to it in the freezer – this will help pinpoint the cause.)