Zircon Docs

The Flash Loan protection mechanism

Zircon has a system designed to prevent value extraction from flash loans and market manipulation.
A Pylon pool will go into lockdown when it detects too large of a liquidity change in the span of one or a few blocks (approximately 4% of the pool’s value in 5 blocks or less). This mechanism is triggered either by enormous swaps, or enormous one-sided additions/removals of liquidity.
The lockdown lasts for a few blocks and allows one “strike” before triggering, so the first large mint/burn can come in undisturbed. The protection acts by first increasing the fee, but above a certain level the transaction will just revert.
If you see very large fees being quoted by the system, it's likely that the pool is under partial lockdown. Wait a few minutes so that it cools down and unlocks itself.