Submitted by broccoli
When an lp provider deposits an imbalance amount of token, a swap fee is applied. HybridPool uses the same _nonOptimalMintFee as constantProductPool; however, since two pools use different AMM curve, the ideal balance is not the same.  ref: StableSwap3Pool.vy L322-L337
Stable swap Pools are designed for 1B+ TVL. Any issue related to pricing/fee is serious. I consider this is a high-risk issue
Calculate the swapping fee based on the stable swap curve. refer to StableSwap3Pool.vy#L322-L337.
maxsam4 (Sushi) confirmed
