This message is issued by the driver (see parse.c or log-1.phpt unit test). This behavior is controlled only by the MongoLog
class (there are no ini options for it), and registration is disabled by default, so you certainly know if you activated it. I guess some codeIgniter related library is the culprit (this is the only general thread I can make out).
You can find more detailed information in the MongoLog documentation , but the following should completely disable logging for all levels and modules:
\MongoLog::setLevel(\MongoLog::NONE) \MongoLog::setModule(\MongoLog::NONE)
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