Hey we had an issue yesterday where the difficulty settings in Arena and Casual PVP were affecting the Vault Troop stats. We fixed this last night or today so the Troop stats are correct according to your Vault difficulty setting only now.
I don’t believe this should have affected your Rewards at all though, especially the Gnome Loot.
So the Troops should be easier to fight but the Rewards will be as intended for the Vault difficulty setting you select now.