clientUser spike repeating at 7pm ET(12am UTC)

[DanielStormApps]

I have an insight that shows users over the last 3 days(72 hours)
Every day at 7pm ET(12am UTC) there is a large spike in the number of users reported in the insight.
Is this a reporting issue?
I have a "heartbeat" report every 10 minutes while the app is in the foreground, is this an indication of how many users have the app foregrounded at the beginning of the measured day? Assuming TD starts the day at 12am UTC.

Insight ID: D8237D9E-C5DC-419E-B551-966F4F105714

{
  "aggregations": [
    {
      "fieldName": "clientUser",
      "name": "count",
      "type": "thetaSketch"
    }
  ],
  "baseFilters": "thisOrganization",
  "dataSource": "telemetry-signals",
  "filter": {
    "fields": [
      {
        "dimension": "isTestMode",
        "type": "selector",
        "value": "false"
      }
    ],
    "type": "and"
  },
  "granularity": "hour",
  "queryType": "timeseries",
  "relativeIntervals": [
    {
      "beginningDate": {
        "component": "day",
        "offset": -3,
        "position": "beginning"
      },
      "endDate": {
        "component": "day",
        "offset": 0,
        "position": "end"
      }
    }
  ]
}