1. When the Campaign IsActive is flipped to FALSE, I am updating related Campaign Members
2. When the Campagin IsActive is flipped to FALSE, I am updating related Leads (Leads are related directly via a custom field called Current_Campaign_ID__c).

trigger deactivateCampaignMember on Campaign (after update) {


//HANDLE UPDATING CAMPAIGN MEMBERS RELATED TO CAMPAIGN
    Set<ID> campids = new Set<ID>();
    for(Campaign camp : Trigger.new){
            campIds.add(camp.Id);
    }

    List<Campaign> updatedCampaigns = [SELECT Id, IsActive, (Select Id, Campaign_IsActive__c from CampaignMembers)  FROM Campaign WHERE Id in :campids];
    List<CampaignMember> campMemsToUpdate = new List<CampaignMember>();

    for (Campaign camp : updatedCampaigns){

        for(CampaignMember cm : camp.CampaignMembers){
            if(camp.IsActive == False){
            cm.Campaign_IsActive__c = False;
                if(cm.Campaign_Lead_Status__c == 'In Campaign'){
                    cm.Campaign_Lead_Status__c ='Resting';
                    campMemsToUpdate.add(cm);
                    
                }
            }
        }
    }
    
    
//HANDLE UPDATING LEADS RELATED TO CAMPAIGN    
        Set<ID> campids2 = new Set<ID>();
        for(Campaign camp2 : Trigger.new){
                campIds2.add(camp2.Id);
        }   
        List<Campaign> updatedCampaigns2 = [SELECT Id, IsActive, (Select Id, Current_Campaign__c, Current_Campaign_ID__c, Status from Leads__r)  FROM Campaign WHERE Id in :campids2];
        List<Lead> campLeadsToUpdate = new List<Lead>();
    
        for(Campaign camp2 : updatedCampaigns2){
        
            for(Lead ld : camp2.Leads__r){
                if(camp2.IsActive == False){
                    if(ld.Status == 'In Campaign'){
                        ld.Status = 'Resting';
                        ld.Current_Campaign__c = '';
                        ld.Current_Campaign_ID__c = NULL;
                        campLeadsToUpdate.add(ld);
                    }
                }    
            }
        }
    update campMemsToUpdate;
    update campLeadsToUpdate;
 }