Everyone uses some third-party plugin or library. In the software community, it is inevitable that you will have to depend on someone else's code. What you don't know when you use that code is the quality, stability, and ability to meet your future needs.

With that in mind, it is a bad idea to rely directly on the classes and interfaces presented to you by that third-party. Instead, use a hexagonal architecture, also known as ports and adapters. For anyone doing C#, this includes abstracting the .NET framework.

Any code that you and your team did not write should be abstracted to protect your code from the potential external changes. This includes code written at your company but by a different team. If it is outside your control, put it behind an abstraction. The preferred abstraction is one or more interfaces that provide the desired functionality.