Well, yes, roots do squeeze their way into pipes underground because they get thirsty just like humans. Main sewer lines are put together in sections or pipe. Older pipes are more prone to having root intrusion but newer clay or pvc pipes get root growth as well.
That was a long root and we pull those out off clients sewer lines all the time. People who choose to neglect with sewer line and don’t schedule yearly cleanings end up having to excavate sooner. Bottom line clean your sewer line yearly and take off your properties.