I wonder if sea cables could be designed with some mechanism that could stand being dragged and even crossed somewhere but returning later to its position automatically with a click. Something like a giant karabiner.
I'm sure it could, but whether it's cheaper than the existing cable and repairs is probably the question mark
The main expenses aren't so much the value of the cable as the disruption in communication and intelligence that could be sensible. Arranging the cable like a V ending in a karabiner in the angle could catch the anchors on a big area and redirect it toward the point of breaking and release anchor at the angle. If the ship would take a long detour from the shortest path to attack the cable in a different area, that would coast then gas money, so a possible boycott is not free anymore making the process less desirable.
That also would eliminate the plausible deniability of the ship that moved out of its main route, and could reduce the cut of communications to hours or minutes (instead days or weeks).
Just speculating