See https://github.com/mongodb-js/mongodb-core/blob/837f31276d77cea9838f1ad907dc63650a042200/lib/wireprotocol/command.js#L132

In our command construction, we are automatically adding a readConcern.afterClusterTime to every command that has a session. The Causal Consistency spec only says to add afterClusterTime to read commands, and explicitly says to not add it to runCommand-like behavior.

While this will likely not break anything in the server, it does cause some errors when attempting to comply with spec tests that assert whether or not a readConcern is present