RDS measures network traffic to and from each DB instance and Blue Matador watches the NetworkReceiveThroughput and NetworkTransmitThroughput metrics for anomalies that suggest your applications are querying RDS in an unexpected way. These metrics include traffic to the instances as well as traffic produced through Cloudwatch monitoring and replication. Issues in network traffic are often sure signs that there are problems in your infrastructure.
It’s likely that this anomaly is caused by queries your application is submitting to your database. If your DB instance is sending a lot of data, it’s likely a SELECT query that’s to blame; if it’s receiving a lot of data, it’s likely an UPDATE or INSERT query. To get further information, you can check logs for the database from the RDS console.