There's this restriction in the config for the damage that doesn't allow more than 20 health of damage. https://github.com/blay09/ForgivingVoid/blob/1.12/src/main/java/net/blay09/mods/forgivingvoid/ModConfig.java#L12
This should be changed since mods that increase health exist and I would always like to leave the player with half a heart no matter what his maximum health is. With the actual config if the player has more than 10 hearts there's no way to give him damage down to half a heart.