@Arceusl - 0 - 14 for node light levels, 15 for sky light levels (natural light).
But why then? If 15 is the maximum, why bother having only 0-14 be for nose sources, when 15 is the maximum? In Minecraft this wouldn't be a problem at all, here in MineTest it does create problems now.
@Arceusl - Multiplant mod has been updated with the light fix.
Resolves that mistake.
Also, I'm currently refusing the 5.17 update for Luanti, I have my reasons, because I'm still extremely concerned about an absolute breakdown of the Android application again.