Submitted by peritoflores, also found by WatchPug
https://github.com/code-423n4/2022-06-nibbl/blob/8c3dbd6adf350f35c58b31723d42117765644110/contracts/Twav/Twav.sol#L28
https://github.com/code-423n4/2022-06-nibbl/blob/8c3dbd6adf350f35c58b31723d42117765644110/contracts/Twav/Twav.sol#L40
Contract will break when cumulativeValuation overflows.
Cumulative prices are designed to work with overflows/underflows because in the end  the difference is important.
In _updateTwav()  when _prevCumulativeValuation + (_valuation *_timeElapsed)  overflows the contract will not work anymore.
Same  problem in _getTwav()
https://github.com/code-423n4/2022-04-phuture-findings/issues/62
Add unchecked keyword in every line you add / subtract cumulative prices.
mundhrakeshav (Nibbl) acknowledged 
HardlyDifficult (judge) decreased severity to Medium and commented:
