At level 6, the Thumper can distinguish between tier 1-2 ore, and tier 3-4 ore.

Upon upgrading to level 7, the Thumper loses this ability, and all ore below tier 5 appear the same.

Why does this upgrade negatively affect the Thumper's usefulness?

My suggestion:
As the Thumper improves, it should gradually reveal more information about hidden ore, and at max level identify each specific ore.

If not that detailed, at least 3 colors to represent tier 1-2 ore, tier 3-4 ore, and tier 5 ore.