[THE Xecron]

Unfortunately, I cannot tell you for certain whether it is just a display bug. however in battle it does say

Motherly Felidae: Prototype A (8 Power).

I will try and obtain two shotguns of the same power and compare an upgraded one with the un-upgraded version to see if there is a hidden power difference.

Until I post otherwise, we shall assume it has been fixed.

UPDATED: I can confirm it was a display error as seen with below.

Motherly Felidae: Floating Galdric Shotgun (8 Power)
Hit: redacted
Dmg: 33
Crit: redacted
Critical Hit! Motherly Felidae attacks Imperialist Arena Combatant with Floating Galdric Shotgun and hits them!
Imperialist Arena Combatant takes 124 Pierce damage.
Imperialist Arena Combatant takes 10 Wind damage.
Motherly Felidae's turn.
Motherly Felidae: Prototype A (8 Power)
Hit: redacted
Dmg: 33
Crit: redacted
Critical Hit! Motherly Felidae attacks Imperialist Arena Combatant with Prototype A and hits them!
Imperialist Arena Combatant takes 133 Pierce damage.
Imperialist Arena Combatant takes 10 Wind damage.
Motherly Felidae's turn.

As you can see, Prototype(Upgraded) does more pierce damage, indicating an increase in power.