Ge(Il)compounds are powerful reducing agents whereas Pb(IV)compounds are strong oxidants .It is because

The inert pair effect is the unwillingness of s-electrons to participate in bonding. In heavier metals, inert pair effect is more evident where s-electrons exhibit inert behavior and do not engage in bonding with other elements.

Both Ge and Pb are group-14 elements and show two oxidation states: +4 and +2. Due to inert pair effect, +2 oxidation state of Pb is more stable than the +2 oxidation state of Ge. Therefore, Ge(II) tends to acquire Ge (IV) state by loss of electrons, as a result acts as a reducing agent. While, Pb (IV) tends to acquire Pb (II) by gaining of two electrons, thereby acts as strong oxidizing agent.