Zeff and ionization energy

[Ashley R 1A]

What exactly is the connection between increasing effective nuclear charge (Zeff) and ionization energy increasing across a period? I understand that Zeff increases as you move down, but I'm getting lost on how it's connected to the ionization energy.

[Myka G 1l]

The higher the effective nuclear charge, the greater the pull of electrons to the nucleus. Therefore, the electrons will be harder to remove when the ENC is higher and the ionization energy will be higher.

[Jada Brown 2H]

As you move across a period, there are more protons in the nucleus of each atom which creates a greater pull on electrons. This in turn causes the ionization energy to increase as well.

[Elizabeth Harty 1A]

Ionization energy is the minimum energy required to remove one mol of electrons from one mol of an atom. Therefore, the tighter the hold on the electrons, the higher the ionization energy is as it is more difficult to remove said valence electron. Species with higher effective nuclear charge have a tighter hold on the electrons and therefore a higher ionization energy.

[Siddiq 1E]

Doesn't nuclear charge decrease down a group? I'm confused as to why the trend doesn't follow the ionization energy trend exactly.