Hi @RBMK_Blaze ,
First, as a quick disclaimer, the C# driver does not officially support Unity at this time. Based on the stack trace you provided, this appears to be a Mono issue rather than the driver itself. Both stack traces seem to point to something involving assembly_name at the top.
To help isolate the issue, I recommend testing whether the problem occurs with a minimal example. For instance, try running the following line to see if it crashes:
typeof(IMongoClient).GetTypeInfo().Assembly;
Let me know how it goes!