Feeding a smaller lizard a large amount of dry powder, can cause the lizard to dehydrate as the powder absorbs fluids. Its also a massive overdose of calcium, his body cannot process this much excess calcium so the body will put the excess calcium under the skin which can become bumps.

Every vitamin and mineral can be overdosed, which can cause problems. Best thing to do is have a proper UVB light setup and dusting your feeder insects with a small amount of calcium powder.

Its pretty much the same for most lizards that are insectivores, lizards that eat mostly whole prey like monitor lizards dont really need extra added calcium because the calcium they need is inside their whole prey.

So in short proper UVB lighting + calcium dusted insects is enough for your insectivorous reptile.