Make sure not to pry too much under the flex cable because you will likely damage the gold / silver shining adhesive tape that is located beneath it.

The guide is missing a comment on this and one would not expect the tape there. Check out the photos of step 10 to get an idea of how the tape looks like.

I assume this to be some kind of head-conductive component.

It won't be much of a problem if you damage parts of it though.

But if you peel off / coil up too much of it, it could get too big and the flex cable could get damaged when it's pressed against it.