Final Fantasy XVI: Finding The Voices Of Clive And Joshua Rosfield

The initial voice actor for Joshua began recording lines but hit puberty midway, rendering him unable to sound like an 8-year-old anymore.

Even though CBUIII has cast a Japanese voice actor for Clive, Yoshi-P still plays the game in English due of Ben Starr's performance

Source: https://www.gameinformer.com/exclusive-feature/2023/05/30/final-fantasy-16-finding-the-voices-of-clive-and-joshua-rosfield