Calling a method using delegate makes my object null

Hi I tried making a event delegate that calls function A where function A repeatedly calls function B using a reference. Whenever function A gets called using the event delegate, at the first call for function B a variable in function B (Variable B) is not null. The problem starts at the second loop call of function B, because variable B becomes null. The weird part about it is that I tried not using the event delegate to call for function A, and called it using a reference instead and it works so that variable B does not return null on the succeeding calls. Do delegates somehow remove objects?

Here is my delegate located in Script A:

         public delegate void DelegateEventHandler(EntityCard p_card, List<EntityCard> p_generalList, int index);
         public static event DelegateEventHandler filterDelegate;
 
     public static void DelegateCall(EntityCard p_card, List<EntityCard> p_generalList, int index)
     {

         if(filterDelegate != null)
         {
             filterDelegate(p_card, p_generalList, index);
         }
     }

It is called in the same script (Script A) using:

 foreach (var card in m_currentFilterList)
 {
     DelegateCall(card, m_groupedList, i);
 }

Script B is registered to the delegate with function A:

      void OnEnable(){
         
         CardFilter.filterDelegate += this.FunctionA;
     }
     
     void OnDisable(){
         
         CardFilter.filterDelegate += this.FunctionA;
     }

             public void FunctionA(EntityCard p_card, List<EntityCard> p_generalList, int index)
             {
                         GameObject gridCards = m_cardPooler .FunctionB (containerName [index]);
             }

Function B in Script C is called by Function A in Script B:

 public Queue[] VariableB;
 
 public GameObject FunctionB (string p_containerType)
         {
         for(int i=0; i < m_containers.Length; i++)
         {
             if(m_containers[i].containerType == p_containerType)
             {

                 if(VariableB == null)
                 {
                     Debug.Log("NULL QUEUE LIST");
                 }
                 else{
                     Debug.Log("HAS QUEUE LIST");
                 }

                                     return something;
             }

         }

         return null;

     }