I have a TNT arrow, and it should have a "Fuse" NBT-tag. I already tried that:

	@Override
	public CompoundTag serializeNBT() 
		CompoundTag tag = super.serializeNBT();
        tag.putInt("Fuse", getFuse());
        return tag;
    }

    @Override
    public void deserializeNBT(CompoundTag tag) {
        super.deserializeNBT(tag);
        setFuse(tag.getInt("Fuse"));
    }

but it didn't help

Topic closed. I solved it like this:

@Override
    public void addAdditionalSaveData(@NotNull CompoundTag tag) {
        super.addAdditionalSaveData(tag);
        tag.putInt("Fuse", getFuse());
    }

    @Override
    public void readAdditionalSaveData(@NotNull CompoundTag tag) {
        super.readAdditionalSaveData(tag);
        if (tag.contains("Fuse")) {
            setFuse(tag.getInt("Fuse"));
        } else {
            setFuse(80);
        }
    }