Discoloration of some sprites

I’ve noticed with a few of my games (A Link to the Past and Donkey Kong Country) there are some issues with discoloration of some of the sprites. In ALTTP, some of the enemy sprites have more muted colors (red enemies appear purple, and green enemies more of a lighter green) and in Donkey Kong Country, Donkey Kong, when in game, appears yellow and slightly distorted, but all the other sprites, including donkey kong when not playable, are normal. Any Idea what could be causing this? I’ve used both the RF port and the A/V ports, with different cables, but the discoloration is still present.