That's because the op25.i isn't declaring any destructors.  The minimum fix is to change that for our code but what's really required is to update our for GNURadio 3.6 and that means switching to a cmake build, renaming code, splitting impl/interface, dropping obsolete interfaces and making use of new features. If we go that far then there's a heap of other stuff to do. I am about to write another email about that.