The problem is generated map. It's unbalanced distribution of bases.
Bubbles don’t droop only on 20 + area,it seems they drop also by breaching certain distance from the center, which is 275 fields on that server. The rules seems to be unlcear.
In W it is area 12-14 on S it’s 15-16 area, and on mixed sectors area 22 is further from center than 290 fields, but bubbles drop because it is 20+ area.
So you can kill several 12 bases, and reach the limit, have worse resources but spend CP or drop the bubble and attack 16 lvl base an still have worse resources gain than someone that started next to 22 base and didn't make any move.