Submitted by said, also found by peakbolt and HChang26
https://github.com/code-423n4/2023-08-dopex/blob/main/contracts/core/RdpxV2Core.sol#L843-L847 
https://github.com/code-423n4/2023-08-dopex/blob/main/contracts/core/RdpxV2Core.sol#L699-L744
Current design allow user call bondWithDelegate using decaying bonds, this will make delegatee incur loss because they will get less bond and paid more eth.
When users have decaying bonds, they can either utilize it via bond or bondWithDelegate. If user choose to use bondWithDelegate, they need to provide _delegateIds (delegated eth that can fulfill the request).
https://github.com/code-423n4/2023-08-dopex/blob/main/contracts/core/RdpxV2Core.sol#L819-L885
Then it will call _bondWithDelegate to calculate rdpxRequired and wethRequired and reduce delegatee provided collateral by increasing activeCollateral with  wethRequired. Then calculate the bond received by calling _calculateAmounts, this will based on delegate.fee, wethRequired and rdpxRequired.
https://github.com/code-423n4/2023-08-dopex/blob/main/contracts/core/RdpxV2Core.sol#L699-L744
If user using decaying bonds, when call calculateBondCost and calculating rdpxRequired and wethRequired, it will not use any discount, this will make wethRequired even more bigger considering that if putOptionsRequired is true. delegatee need to paid premium that based on rdpxRequired (that not discounted).
https://github.com/code-423n4/2023-08-dopex/blob/main/contracts/core/RdpxV2Core.sol#L1156-L1199
This means, delegatee need to paid undiscounted wethRequired plus undiscounted premium!
This will make delegatee would not want to fulfill bondWithDelegate when decaying bond is used. Delegatee can front-run by withdrawing his delegated assets before bondWithDelegate  with using decaying bonds calls.
PoC Foundry :
Comparing fulfilling bondWithDelegate requests in 2 scenarios, with decaying bonds and non-decaying bonds.
Add this test to Unit contract inside /tests/rdpxV2-core/Unit.t.sol, also add import "forge-std/console.sol"; in the contract :
Run the test :
Test Output :
It can be observed delegatee paid weth more with decaying bond and receive less bond share.
Consider to restrict bondWithDelegate for only non-decaying bonds. Or also add discount but apply only to the weth part if called from bondWithDelegate.
Alex the Entreprenerd (Judge) commented:
 Making primary because this warden sent the POC before any request.
