Filtering on child properties in GraphQL

I am using GraphQL to get a list of upcoming events. I am having trouble finding the correct way to filter on the date value which is a child of my date field.

The query, which works:

query getUpcomingEvents {
  nodeQuery(
    filter: {
      conditions: [
        {operator: EQUAL, field: "type", value: ["ain_event"]},
        {operator: EQUAL, field: "status", value: ["1"]} 
      ]
    }
  )
  {
    entities {
      entityLabel
      ...on NodeAinEvent {
        fieldAinEventLocation
        fieldAinEventDate {
          startDate
          endDate
        }
        fieldAinLink {
          uri
        }
      }
    }
  }
}

I get this response:

 {
  "data": {
    "nodeQuery": {
      "entities": [
        {
          "entityLabel": "EAA AIRVENTURE",
          "fieldAinEventLocation": "OshKosh, WI",
          "fieldAinEventDate": {
            "startDate": "2021-07-26 12:00:00 UTC",
            "endDate": "2021-08-01 12:00:00 UTC"
          },
          "fieldAinLink": {
            "uri": "http://www.eaa.org/en/airventure"
          }
        },
        {
          "entityLabel": "FlightSimExpo",
          "fieldAinEventLocation": "San Diego, CA",
          "fieldAinEventDate": {
            "startDate": "2021-09-24 12:00:00 UTC",
            "endDate": "2021-09-26 12:00:00 UTC"
          },
          "fieldAinLink": {
            "uri": "http://www.flightsimexpo.com/"
          }
        },
        {
          "entityLabel": "Sun 'n Fun",
          "fieldAinEventLocation": "Lakeland, FL",
          "fieldAinEventDate": {
            "startDate": "2020-03-31 12:00:00 UTC",
            "endDate": "2020-04-05 12:00:00 UTC"
          },
          "fieldAinLink": {
            "uri": "https://www.flysnf.org/"
          }
        }
      ]
    }
  }
}

I tried adding this, to no avail:

{operator: GREATER_THAN_OR_EQUAL, field: "fieldAinEventDate.startDate", value: ["2021-07-25 12:00:00 UTC"]}

Found the answer - apparently the fields are referenced differently in the filter conditions. This works:

{operator: GREATER_THAN_OR_EQUAL, field: "field_ain_event_date", value: ["2021-07-25 12:00:00 UTC"]}

The important info here comes from a comment in the issue @Kevin referenced.

You can only query the fields available on the entity.

This is because your query is eventually converted to an entityQuery. You must reference fields and their properties as Drupal understands them, not how they're shown when returned from a GraphQL query.