I have noticed as I convert t2 attacks to t3 l3 attacks I keep getting slightly less ap and bp (ally plunder and base plunder) I used to get seven mill a hit, now I get five after converting one.
That's because plunder is based on the relative strength of your troops to the opponent. And you became stronger so yeah.
What target are your testing your plunder on? Since you are upgrading, you are getting stronger, and so as you grow you need bigger targets. If you continue to hit smaller targets as you grow, you'll earn less and less plunder. That's why large players make next to no money when hitting a small player.
Yes Alex. Also, I just upgraded a guild and now my plunder is higher than it was so bye Mod, please lock this thread.