Disco 2 Lost white and brown wire from stereo change, should I be worried?

I've swapped out one aftermarket stereo for a newer one. The old one was connected to a CD changer and GPS under the driver/passenger seats, so I spent ages pulling out wires to make sure I got everything.

The last thing I managed to sort was what might have been a power supply block. In addition to the thick black cables in and out was another thin white and brown wire that disappeared up behind the stereo somewhere along with a few others. Unfortunately while I was trying to trace it, it seemed to snap and I can't find any trace of it any more. The rest of the bunch all tuned out to be spliced off from the ISO harness, so I'm hoping it was the same.

Does this seem likely? I'm guessing it could be an ignition signal for turning the power block on and off - but equally could be a signal for turning on the GPS unit when the old screen was activated. I know that it'll depend a lot on what the installer chose to use, but should I worry enough to go looking for it? Everything seems to work fine now, I've not noticed anything odd since losing it.

You should fine where it ‘snapped’ and isolate it in case its live, as that’s a fire risk right there.

However, hopefully someone might come along and be able to tell you what’s it’s for, and you may not need to bother

Judging by the diagram on page 47 of the manual (https://www.manualslib.com/manual/366096/Vdo-Mr6000.html?page=47#manual) I'm guessing the box I found was the adapter box, which would make the wire the mute cable. Unfortunately the stereo pieces were stolen from outside, so I can't go and check anything any more, but the top image here https://www.drive2.ru/l/765332/ would seem to support this.