As a part of PM-3364 after SERVER-81189 the {create..} command instead of running directly against the primary will run _shardsvrCreateCollection on the primary which creates the collection.

However, in case {create...} runs a part of a transaction, the following check is perform on mongos which fails in case of _shardsvrCreateCollection due to CommandHelpers::findCommand since the command is only present on shard servers 

As a part of SERVER-81189 a simple fix was added to  force returning false in case of _shardsvrCreateCollection: https://github.com/mongodb/mongo/search?q=SERVER-82282&type=Code

There is no good reason to fail in case the command is not found since this check is already performed by the entry point . 

The helper should probably instead either:

• return default false in case a command is not found
• perform the check on the shard instead of mongos 
• Any other solution that can make the code better maintainable