offerId is a field in struct LoanOffer (src/interfaces/loans/IMultiSourceLoan.sol#L26) and LoanOffer is typically signed by the lender. Currently, offerId is generated off-chain and its correctness is verified through _checkSignature(lender, offer.hash(), _lenderOfferSignature (src/lib/loans/MultiSourceLoan.sol#L780) in the emitLoan flow.
But when the lender is a pool contract, offerId will not be verified due to _checkSignature() being bypassed in _validateOfferExectuion() (src/lib/loans/MultiSourceLoan.sol#L777). 
A borrower can supply any offerIds for a pool lender offer in emitLoan() or refinanceFromLoanExeuctionData() flow. As a result, emit LoanEmitted(loanId, offerIds, loan, totalFee) or emit LoanRefinancedFromNewOffers(_loanId, newLoanId, loan, offerIds, totalFee) will contain arbitrary offerIds. This may create conflicts in off-chain offerId accounting.
If offerId for a pool lender is relevant, consider allowing a pool contract to increment and store its next offerId on-chain.
