I’m no audiophile, but wouldn’t that plug fit into the port right next to it?
Headphone jack is an output. The jack they’ve hotwired is an input.
It’s hard to tell with the wire covering part of the label.
You can see enough to tell it’s an I (in), not an O (out) - plus the fact there’s only room for one more letter behind the copper, as demonstrated by the hidden P in “TAPE” above. Having dealt with this sort of equipment enough in my life, those were really the only two possibilities.