MutateIn modifies global Transcoder setting, possibly corrupting data for all other operations.

CouchbaseCollection.MutateInAsync does the following to copy Serializer from per-operation options.

However, mutation.Transcoder may be a reference to the Singleton-registered OperationConfigurator.JsonTranscoder.  So if a call to MutateIn specifies a custom ITypeSerializer in the options, then all future mutation operations will use that ITypeSerializer.

The core of the problem is that nothing registered as a Singleton should be mutable in the first place.