Sample Code:

import * as amplitude from "@amplitude/analytics-browser"

const args = {
  "event": "raw_test_event",
  "event_label": "Some label",
  "some_boolean": false,
}

amplitude.track(args.event, args)

What is being sent to amplitude:

event_properties: {
  "event": "raw_test_event",
  "raw": {
    "event_label": "Some label",
    "some_boolean": false,
    }
  },
  "gtm.uniqueEventId": 123
}

Expected:

event_properties: {
  "event": "raw_test_event",
    "event_label": "Some label",
    "some_boolean": false

}

SDK version: 2.1.3

Workaround:

It seems to be related to the key “event”. Using a different key like “event_name” fix the problem and it works as expected.

Question:

Why is this happening? It appears to be a reserved property, I did not find any documentation explaining this behaviour.