Nothing to fix. The new xp system is meant to encourage wars, not individual unit farming. When your entire surviving army has a few +1 hp and damage, it becomes significantly more powerful. When it’s only 10 units or so, it does little (which was so that people could no longer affect the outcome of an entire war with just a few xp units they farmed from 1 or 2 battles). You can still receive high stats for individual units, but that requires a LOT of experience to achieve (and is discouraged). Constant warring and big battles should reward stronger units. Not sitting all era killing a few small fries and then you are suddenly so OP the top alliance can’t handle you.