Unit value in RDS CloudWatch Alarm is Null

Hello,

I have been trying to obtain a value from an SNS message passed from a CloudWatch Alarm for the DatabaseConnections Metric. The value of the Unit is null hence I cannot parse the message to obtain the DBIdentifier value. Is there a reason why the CloudWatch alarm does not have a value for the Unit? Looking at the AWS RDS documentation, the value for DatabaseConnections Metric, Unit should be Count but the alarm gives null. https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/rds-metrics.html#rds-cw-metrics-instance

Below is the message obtained from the SNS message body:

{
    "AlarmName": "awsrds-poc-test-High-DB-Connections",
    "AlarmDescription": "When the DB-Connections is lower than 1",
    "AWSAccountId": "<##########>",
    "AlarmConfigurationUpdatedTimestamp": "2022-06-17T08:54:32.735+0000",
    "NewStateValue": "ALARM",
    "NewStateReason": "Threshold Crossed: 1 out of the last 1 datapoints [0.0 (17/06/22 08:50:00)] was less than the threshold (1.0) (minimum 1 datapoint for OK -> ALARM transition).",
    "StateChangeTime": "2022-06-17T08:55:15.402+0000",
    "Region": "US East (N. Virginia)",
    "AlarmArn": "arn:aws:cloudwatch:us-east-1:678932343753:alarm:awsrds-poc-test-High-DB-Connections",
    "OldStateValue": "OK",
    "OKActions": [],
    "AlarmActions": [
        "arn:aws:sns:us-east-1:678932343753:sns-alarm"
    ],
    "InsufficientDataActions": [],
    "Trigger": {
        "MetricName": "DatabaseConnections",
        "Namespace": "AWS/RDS",
        "StatisticType": "Statistic",
        "Statistic": "AVERAGE",
        "Unit": null,
        "Dimensions": [
            {
                "value": "<######>",
                "name": "DBInstanceIdentifier"
            }
        ],
        "Period": 300,
        "EvaluationPeriods": 1,
        "DatapointsToAlarm": 1,
        "ComparisonOperator": "LessThanThreshold",
        "Threshold": 1,
        "TreatMissingData": "",
        "EvaluateLowSampleCountPercentile": ""
    }
}