type
TMyClass = class(IMyInterface);
......
procedure Test(anObject : TObject = nil)
begin
  if not Assigned(anObject) then
  begin
    anObject := TMyClass.Create;
    anObject.Init;
  end; //Delphi 10.4 destroys IAutoFree here
  ... some other code
end; //Delphi 10.3 destroys IAutoFree here

..........
type

  IMyIntf = interface
    procedure InitProz;
  end;

  TMyClass = class(TInterfacedObject, IMyIntf)
  public
    procedure InitProz;
  end;
..............
procedure TMyClass.InitProz;
var a: integer;
begin
    a := 1;
end;


procedure TForm1.Test(anObject : TMyClass = nil);
begin
  if not Assigned(anObject) then
  begin
    anObject := TMyClass.Create;
    anObject.InitProz;
  end; //Delphi 10.4 destroys anObject here
  anObject.InitProz;
end; //Delphi 10.3 destroys anObject here

procedure TForm1.Button2Click(Sender: TObject);
var obj: TMyClass;
begin
  Test;
end;