In the transition metals, $4s$ has a higher energy level than $3d$, because in ionization, the electrons from the $4s$ energy level are lost first.
I was thinking that this might be the same for much of the p-block from elements Ga-Rn because:
Ga has a electron configuration of: $1s^22s^22p^63s^22p^63s^23p^63d^{10}4s^24p^1$
Ga$^{3+}$ has an electron configuration of: $1s^22s^22p^63s^23p^63d^{10}$