Interestingly, fiber signals can be split passively[1] (without a transducer), which should be extremely reliable. No idea what technology this kind of application would use though.
We don't know the architecture of this hypothetical spy splitter tho in the current case. It can be less covert and more of a complicated config, etc.
How often does the entire west coast of the U.S. lose Internet connectivity to the entire continent of Asia? That gives you a constraint on how often that type of failure actually occurs.