The formula is currently set to evaluate if the $CustomMetadata.inov8__PMT_Setting__mdt.inov8__Default.inov8__Start_Month_of_Fiscal_Year__c < 0 which will always be false and this will make it so the value of the fiscal year always adds a +1. This should be updated to $CustomMetadata.inov8__PMT_Setting__mdt.inov8__Default.inov8__Start_Month_of_Fiscal_Year__c > 0