If you see soft poop, then, stop feeding all vegetables until after poops return to normal. Over 80% of their diet should be hay.
Please do not feed kale and carrot regularly. Kale is far too high in calcium to be fed anything more than once a week and even then it needs to be in small amounts. Carrot is too high in sugar and should only be a very occasional treat.
The link below shows a sample plate of vegetables that can be fed daily, and links to a list of veg which needs to be limited
Long Term Balanced General And Special Needs Guinea Pig Diets