Metric count differs by day between versions

Hi there,

We collecting Klaviyo events performance and we going to migrate to the new date-versioned API.

To be sure that we’ll not face the data discrepancy after migration, I’ve compared data from endpoints in both API versions: v1 and 2023-02-22.

1. In the v1 API we used endpoint metric/{metric_id}/export , filtering data with $attributed_message value (aka campaign ID).

E.g., I’ve sent the following request for metric NjaHUp "Placed Order" and $attributed_message 01GW284VK0V70JNJY8ZC5WMEPN:

curl -L -g -X GET 'https://a.klaviyo.com/api/v1/metric/NjaHUp/export?start_date=2023-03-21&end_date=2023-03-25&where=[["$attributed_message","=","01GW284VK0V70JNJY8ZC5WMEPN"]]&api_key={api_key}'

and got these data:

{"date": "2023-03-21 00:00:00",

"values": [2.0]},

{"date": "2023-03-22 00:00:00",

"values": [4.0]},

{"date": "2023-03-23 00:00:00",

"values": [5.0]},

{"date": "2023-03-24 00:00:00",

"values": [2.0]},

{"date": "2023-03-25 00:00:00",

"values": [3.0]}

2. In the date-versioned API I’ve found the endpoint metric-aggregates/. It allows to define breakdowns in the “by” parameter, and it’s a cool feature in fact!

However, sending request for the same metric: 
curl -L -X POST 'https://a.klaviyo.com/api/metric-aggregates/' \
-H 'Authorization: Klaviyo-API-Key {api_key}' \
-H 'revision: 2023-02-22' \
-H 'Accept: application/json' \
-H 'Content-Type: application/json' \
--data-raw '{
  "data": {
    "type": "metric-aggregate",
    "attributes": {
      "metric_id": "NjaHUp",
      "interval": "day",
      "measurements": [
        "count",
        "unique",
        "sum_value"
      ],
      "filter": [
        "greater-or-equal(datetime,2023-03-21T00:00:00)",
        "less-than(datetime,2023-03-26T00:00:00)"
      ],
      "by": [
        "$attributed_message"
      ],
      "page_size": 500,
      "timezone": "UTC"
    }
  }
}'

I’ve got slightly others values for "dimensions": ["01GW284VK0V70JNJY8ZC5WMEPN"]:

"measurements": {

"count": [

1.0,

5.0,

3.0,

4.0,

3.0

],

I’ve compared these values day-by-day and found that total metrics count for requested period is the same but for single date most values differs:

AFAIK, v1 API uses UTC both in request parameters and response data.

And for revision 2023-02-22 I used "timezone": "UTC" too (however, the response datetimes returned will be in UTC as described in API doc). 

Could you please clarify what’s a reason for this discrepancy? And how I can fix it and got the same data as for v1 API?

Regards and thanks,

Evgeniy