OperationalFeeMultiplier: PlainDescriptor<number>

A fee multiplier for Operational extrinsics to compute "virtual tip" to boost their priority

This value is multiplied by the final_fee to obtain a "virtual tip" that is later added to a tip component in regular priority calculations. It means that a Normal transaction can front-run a similarly-sized Operational extrinsic (with no tip), by including a tip value greater than the virtual tip.

// For `Normal`
let priority = priority_calc(tip);

// For `Operational`
let virtual_tip = (inclusion_fee + tip) * OperationalFeeMultiplier;
let priority = priority_calc(tip + virtual_tip);

Note that since we use final_fee the multiplier applies also to the regular tip sent with the transaction. So, not only does the transaction get a priority bump based on the inclusion_fee, but we also amplify the impact of tips applied to Operational transactions.