John 8:58 is simply not a quote of Ex. 3:14.
A little learning can be a dangerous thing but so can an automobile. Still we must drive.
To some it seems that it is. Thus they conflate "I am" of Jn 8:58 with "that I AM sent you" of Ex 3:14, insisting that any time Jesus says ego eimi he is saying "I AM" (God), namely that he is using eimi as his sacred name and not as a predicate.