Since you brought up changing your vote perhaps you can look into how that works. As I understand it (but I could be wrong and have not searched into the code), changing a vote from 20% to 21% takes mana of a 21% vote, not a 1% vote (and in addition forfeits any curation rewards that the original 20% vote may have earned). This creates an incentive to split ones stake up into tiny pieces so that instead of changing a vote one can just add another 1% from a different account.

If there is not actually any exploit here (and perhaps it is not the exact one I mentioned but some other one with respect to changing votes), I would also be interested to learn that since the claim has been made to me that there is, and that users without fleets of many small/bot accounts are placed at a disadvantage.