why fast-compare not working but own isEqual function works?

Question

I use memo in my script. I dont know why my data rerenders when I use fast-compare (isEqual) and when I use my own function (isEq) then its not rerender. Why ?

import isEqual from 'react-fast-compare'

function isEq(prev: IColorItem, next: IColorItem) {
  if(prev.activeColor === next.activeColor) {
    return true;
  }
}

// rerenders

const Item = memo(({ color, index, style, activeColor, onPress }: IColorItem) => {
  console.log('render');
  return (
    <Button style={s.center} onPress={() => onPress(color)}>
      <Text>{color}</Text>
    </Button>
  )
  // @ts-ignore
}, isEqual);

// No rerender
const Item = memo(({ color, index, style, activeColor, onPress }: IColorItem) => {
  console.log('render');
  return (
    <Button style={s.center} onPress={() => onPress(color)}>
      <Text>{color}</Text>
    </Button>
  )
  // @ts-ignore
}, isEq);

€:

Item:

  const renderItem: ListRenderItem<ColorsType> = ({ item, index }) => (
    <Item
      color={item}
      index={index}
      style={style}
      activeColor={activeColor}
      onPress={onPress}
    />
  )