Rounding direction favors the user instead of the protocol. Repeated tiny operations accumulate rounding in the attacker's favor, or a single rounding lets shares/assets be minted for free.
// deposit: round shares down; withdraw: round assets down (protocol-favoring)
shares = Math.mulDiv(amount, totalShares, totalAssets, Math.Rounding.Floor);
Largest recorded losses in the same failure class — related, not the same bug:
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