It depends on how the injury happened. If a car hit you while you were riding, the at-fault driver is usually responsible, and their insurance — or your own uninsured motorist coverage — may apply. If a scooter rider struck you as a pedestrian, that rider can be responsible.
If the scooter itself failed — brakes, a wheel, the throttle — a defect or poor maintenance can make the manufacturer or the shared-scooter company responsible. And if a dangerous road, bike lane, or walkway caused the crash, a government agency or property owner may be liable, subject to short deadlines for public entities.
More than one party can be responsible, and identifying every one — driver, company, maker, or property owner — protects your ability to recover. That investigation, and dealing with the company's waiver and arbitration defenses, is a core part of these cases.