Are the two bushes the same variety? If not, it could be that the other variety has a different, more sour, taste. Flavor will vary between varieties. If your bushes are the same type, was the bitter plant producing an unusually abundant crop of berries? If so, those berries can be bitter. When your bush overproduces, you’ll want to be sure to thin the fruit so that the plant can focus on growing fewer berries, and that can help the sweetness. Perhaps another possibility is that the plant is under stress—mechanical injury, disease, environmental, pests, etc. — check to see if the plant looks healthy overall, including the base of the trunk (to check for any damage to bark by weed trimmers, etc).
Are the two bushes the same variety? If not, it could be that the other variety has a different, more sour, taste. Flavor will vary between varieties. If your bushes are the same type, was the bitter plant producing an unusually abundant crop of berries? If so, those berries can be bitter. When your bush overproduces, you’ll want to be sure to thin the fruit so that the plant can focus on growing fewer berries, and that can help the sweetness. Perhaps another possibility is that the plant is under stress—mechanical injury, disease, environmental, pests, etc. — check to see if the plant looks healthy overall, including the base of the trunk (to check for any damage to bark by weed trimmers, etc).