This is the general availability release for the 2.27.0 version of the driver.
The main new features in 2.27.0 include:
Support $sample aggregation operator - CSHARP-2659
Implement Equals method for serializers in LINQ3 - CSHARP-3315
Avoid Appending Write/Read Concern in Atlas Search Index Helper Commands - CSHARP-4839
Disallow comma character in authMechanismProperties connection string value - CSHARP-5106
Fix translation issue during serialization of numbers with differing sizes - CSHARP-5163
Support Linux distros using libdl.so.2 CSHARP-4889
Multiple bug fixes and improvements.
The full list of issues resolved in this release is available at CSHARP JIRA project.
Documentation on the .NET driver can be found here.