That's not a real IF diet. In post time u shouldn't drink ANYTHING instead of water. Large amounts of water to stop hunger. The thing is to fit the caloric demand into a small time.
It does not matter which the version of the IF diet u choose. When you make exceptions to your diet, it's not a real diet anymore. Why anyone should start that diet? Well, to make themself more healthy, to lost some weight in a healthy way. For sure ~300kcal per day isn't the healthier way.