Submitted by cmichel, also found by 0xsanson and WatchPug
The HybridPools reserves are stored as Bento amounts (not Bento shares) in _updateReserves because _balance() converts the current share balance to amount balances.
However, when retrieving the reserve0/1 storage fields in _getReserves, they are converted to amounts a second time.
The HybridPool returns wrong reserves which affects all minting/burning and swap functions.
They all return wrong results making the pool eventually economically exploitable or leading to users receiving less tokens than they should.
Imagine the current Bento amount / share price being 1.5.
The pools Bento share balance being 1000.
_updateReserves will store a reserve of 1.5 * 1000 = 1500.
When anyone trades using the swap function, _getReserves() is called and multiplies it by 1.5 again, leading to using a reserve of 2250 instead of 1500.
A higher reserve for the output token leads to receiving more tokens as the swap output.
Thus the pool lost tokens and the LPs suffer this loss.
Make sure that the reserves are in the correct amounts.
maxsam4 (Sushi) confirmed
