Think this temporary pool size cap is a brilliant idea for the first V3 prize and I’m glad the team have decided to implement it 
What about having separate credit rates which are dependent on the size of the deposit? The higher your deposit, the longer you have to accept it’s locked or else you pay a higher fee than someone who is depositing a small amount.
In this case of the user depositing $1M right before the prize and having a 69% chance of winning is great but what if this would result in both a lower credit rate & higher exit fee.
This would help ensure they keep their funds in the pool & reduce the chance of people trying to game the system by depositing straight before the prize is rewarded and then taking their deposit out immediately after but also protect those who are depositing a smaller amount who aren’t trying to game the system
I guess you could argue than this could maybe result in the whale using many different wallets to deposit the funds but with the gas fees incurred for each transaction, each deposit will make it less and less profitable for the person trying to game the system.