It's a thin layer of protective steel. Nothing as heavy as copper, though. You just need to think about it as plastic, essentially. Not sure how authoritative this source is, but fibre is significantly lighter, according to it!
https://lesolson.com/blog/copper-vs-fiber-optic-cabling-pros-and-cons-for-2024/
Also, fibre can only be bent up to a point, hence the mention of the hook. Ours has a hook in the stonework and then it goes down the downpipe to then enter the property. Since it can only be bent at 90 degrees angles, it does stick out a bit near door frames. We had to use poly fila to make it as close to the door frame to stop the cat from playing with it, as they sometimes do.
The OP doesn't have to worry about the cable. It's meant to be looser and to dangle to allow for flexibility and movement. The soffit is a strange place to attach it to, and I'd have probably attached it to the wall, but if it detaches itself from the soffit, the OP just needs to phone BT/EE, who will then arrange for an OR engineer to redo it.
