Since version 3.0.0 of the library developers have to specify the kind of GuidRepresentation they want to use, usually by registering their `GuidSerializer` globally.
The issue is that `ObjectSerializer` has its own guid serializer inside, that is not affected by the `GuidSerializer` configured globally. This causes confusion in developers, for example here: https://www.mongodb.com/community/forums/t/c-driver-mongo-db-bsonserializationexception-when-using-iaggregatefluentextensions-graphlookup-with-guids/312739

Another issue is that there is no constructor of `ObjectSerializer` that takes only the `BsonGuidRepresentation` as input, but at least developers also need to pass the discriminator convention, that is not something easily understandable.