MutationObserver() vs DOMNodeInserted [duplicate]

I’m having trouble wrapping my head around MutationObserver(). I have an old snippet using DOMNodeInserted which has been depreciated.

The following is a scaled down illustration.

Example

       var d = $(document);

       // DOM Injection/Addition
       d.on('DOMNodeInserted', '*', function (e) {
           $('.ct-cont'    , e.target).addClass('bg-light m-0 p-0 w-100')
           $('.fa-solid'   , e.target).addClass('fa-fw')
           $('.ct-input'   , e.target).css('font-family', 'Courier New');
           return false;
       });

Any assistance would be appreciated and rewarded.