Manage space in legend print composer QGIS

I am struggling to figure out how to manage space in the legend.

I have extra space between some items in my legend, which I would like to remove:

How can I manage these spaces?

I built my legend by adding an extra group layer with the legend items in it stored in 3 different layers (Infrastructure, BAL and Radians).

Every time I used a rule based classification, and it doesn't show any issues for the BAL and Radians groups.

But it doesn't work as I'd like in Infrastructure group. There is extra space between the two NRO and Infra layers.

How can I remove this extra space?

EDIT : here is a screenshot of the legend in the main QGIS window, displaying like I'd like in the print composer.