Derify protocol uses fully objective index with no price curve adjustment, thus blockchain miners cannot gain transaction price advantage through time difference. All profits arise from actual price fluctuation.
Also, all transactions are subject to position restriction, allowed position changes will not create unforeseeable risk to the system. In turn, the system allows all transactions that complies with position restrictions.
There are only two possible scenarios that miners may gain advantage in PCF, though:
Front-running to create a position with same direction to naked position, reducing its PCF payment.
Front-running to create a position with opposite direction to naked position, increasing its PCF reward.
For the first scenario, as long as the attacker pays PCF normally, and the position change is allowed, such actions are considered legitimate.
For the second scenario, miners actually reduce naked position more efficiently, thus we welcome such actions as they reduce risk exposure for the system.
In short, because of Derify protocol's price index mechanism, PCF mechanism and position restriction mechanism, users are not threatened by front-running attacks.