Does MongoDB Atlas C# driver use reflection?

Question about this page in the doc: https://www.mongodb.com/docs/drivers/csharp/current/fundamentals/serialization/class-mapping/.
Specifically “Automatic Class Mapping” paragraph.

How does automatic serialization/deserialization work in C# MongoDB Driver? (POCO->BSON->POCO).
How does the driver know the name of my fields for BSON keys, if I don’t mark them in any way?
I just created a C# class and the driver did all the mapping correctly.

The reason I ask is I want to avoid C# reflection and it feels like there is reflection going on under the hood.

And if it uses reflection, would appreciate if you guide me on how to avoid it.