There is no reentrancy guard in this function, and if used with a token that has transfer callbacks, such as an ERC777, the caller can reenter before balances is updated. I dont currently see a way to exploit this
There is 1 instance of this issue:
https://github.com/code-423n4/2022-05-backd/blob/2a5664d35cde5b036074edef3c1369b984d10010/protocol/contracts/tokenomics/AmmGauge.sol#L130-L135
