DOM removeEventListener issue

Question

I note the following (Javascript removeEventListener not working) I found that details using the same function declaration for both the add and remove event listener calls... Also, this text

But i dont know that either answer my query..

I am not aware and see no reason for the document to be re-rendered for so presumably there is only a single event listenener bound to my function getCurrentElapsedTime()

However, I still cant get this to work.

document.addEventListener('DOMContentLoaded', getCurrentElapsedTime,true);

function getCurrentElapsedTime()
{
    ...
}

function eventFinished($eventFinish)
{// user has completed event...
    document.removeEventListener('DOMContentLoaded', getCurrentElapsedTime,true);
}

When eventFinished is called.. the listener is still running...

In browser console : document.removeEventListener('DOMContentLoaded',getCurrentElapsedTime,true) returns 'undefined'

Help would be appreciated as this has me banging my head against a wall.. thanks in advance

(For the record, ChatGPT also suggests this should work..!)