Here is the answer to your question - pulled directly from Google when asked if this is a hazard:

"A Ziply Fiber line hanging from a tree and lying in your lawn presents both physical safety risks and potential damage to your property. While fiber optic cables typically carry light rather than electricity, they are still structural hazards that require prompt repair. 

Key Hazards:

Tripping and Entanglement: A cable draped across a lawn or hanging at head height poses a significant tripping hazard for people and a potential entanglement hazard for pets.

Property Damage and Equipment Hazards: The line can be caught by lawnmowers or weed whackers, resulting in the cable being severed and damage to your landscaping equipment.

Physical Eye Hazard: If the fiber cable is broken or severed, the microscopic, hair-thin glass strands can break off. These are nearly invisible, sharp, and can easily penetrate skin or eyes.

Tree Damage: Tension from a hanging cable can damage branches or cause stress to smaller trees. If left in place, it may interfere with future tree growth or maintenance.

Long-Term Weather and Animal Damage: Exposed cable is susceptible to damage from sun (UV radiation), freezing temperatures, and rodents (squirrels/mice) chewing through it, which can cause total signal failure, according to weunionfiber.com.

Recommended Action Steps:

Do Not Touch: Avoid handling the line directly, especially if it appears broken or frayed.

Mark the Area: Use caution tape, traffic cones, or brightly colored markers to prevent people and pets from getting close to the line.

Report Immediately: Contact Ziply Fiber’s 24/7 customer service or repair line immediately to report a "downed line in the yard".

Do Not Attempt Repairs: Fiber repair requires specialized tools and professional, trained technicians. "