Hey Oliver,
I don't have a whole lot of experience with Majestic specifically. But Citation flow generally concerns the number of links. This is a good metric to look at, but it's best used in conjunction with trust scores for those links as well. Different tools have different ways of reporting this, but the basic principal is that the quantity of links doesn't matter as much as the quality of them. And if the majority of links come from very low quality sites, it can be a signal to Google that they were earned unnaturally...which puts the site at risk for penalty.
Cherie
