Changed the current HP at level-up will not increase even if the maximum HP increases.
This change was made to prevent skills from becoming inactive due to leveling. This hack has skills that activate when HP is less than half, and there is no skill that requires it to be 100%. Therefore, the fact that the current HP fluctuates with level-up was only a disadvantage (for the conditions of the skill's activation).
Many players may find this more natural, since in recent FE the maximum HP does not increase the current HP, even if the maximum HP is increased.