Length of branches in forest (LaTex)

I’ve written this tree using the Forest package. The output is perfect, but I don’t understand why in order to increase the length of the branch connecting r, I had to write [h, l=2] and not [r, l=2]. Thank you in advance

documentclass[border=0.5cm]{standalone}
usepackage{forest}
forestset{
  empty nodes/.style={
    for tree={calign=fixed edge angles},
    delay={
      where content={}{
        shape=coordinate,
        for current and siblings={anchor=north}
      }{}
    }
  },
}
begin{document}
begin{forest}
[$Omega$, empty nodes
[F]
[($alpha$), l=1.5[G][($beta$)[B][($gamma$)[r][h, l=2]]]]]]]
end{forest}
end{document}