Agreeable Pearl Cricket
Medium
Chainlink recommends for a chain like Optimism, smart contracts must check whether the L2 Sequencer is down to avoid stale pricing. This was not checked in the code.
When the sequencer goes down, oracles will not be up to date ,implying that users would interact with the protocol using stale prices and this could possily results to great loss for the protocol or the users.
If the sequencer goes down, the protocol will allow users to continue to operate at the previous (stale) rates.
Manual Review
Implement check on whether sequencer is down. Example.