Submitted by WatchPug
The actual token withdrawn from vault.withdraw() will most certainly less than the _amount, due to precision loss in _tokensToShares() and vault.withdraw().
As a result, IDetailedERC20(_token).safeTransfer(_recipient, _amount) will revert due to insufficant balance.
Based on the simulation we ran, it will fail 99.99% of the time unless the pps == 1e18.
https://github.com/code-423n4/2021-11-yaxis/blob/146febcb61ae7fe20b0920849c4f4bbe111c6ba7/contracts/v3/alchemix/adapters/YaxisVaultAdapter.sol#L68-L72
https://github.com/code-423n4/2021-11-yaxis/blob/146febcb61ae7fe20b0920849c4f4bbe111c6ba7/contracts/v3/Vault.sol#L181-L187
Change to:
Xuefeng-Zhu (yAxis) confirmed 
