A spike of Ergress to Google IPs causing +735% cost

[nutj]

Hello everyone -- GCP recently charges me +735% over a month due to `Network Internet Egress from Americas to Americas` (see screenshot1). I checks VPC Flow Logs and it shows tons of Ergress traffics to Google IPs (see screenshot2).

Can anyone let me know if this is expected or something is happening with my compute engine and how should I optimise this?

Here's an example of logs:

{
  "insertId": "166ere3f102dql",
  "jsonPayload": {
    "packets_sent": "64",
    "src_vpc": {
      "project_id": "XXX",
      "vpc_name": "default",
      "subnetwork_name": "default"
    },
    "dest_location": {
      "country": "usa",
      "continent": "America",
      "asn": 15169
    },
    "rtt_msec": "24",
    "connection": {
      "src_ip": "10.128.0.4",
      "dest_port": 57883,
      "protocol": 6,
      "dest_ip": "35.186.167.85",
      "src_port": 80
    },
    "start_time": "2022-04-23T11:42:34.601372634Z",
    "reporter": "SRC",
    "end_time": "2022-04-23T11:42:34.650633108Z",
    "src_instance": {
      "region": "us-central1",
      "project_id": "XXX",
      "zone": "us-central1-b",
      "vm_name": "XXX"
    },
    "bytes_sent": "31776"
  },
  "resource": {
    "type": "gce_subnetwork",
    "labels": {
      "subnetwork_name": "default",
      "location": "us-central1-b",
      "subnetwork_id": "XXX",
      "project_id": "XXX"
    }
  },
  "timestamp": "2022-04-23T11:42:38.911994851Z",
  "logName": "projects/XXX/logs/compute.googleapis.com%2Fvpc_flows",
  "receiveTimestamp": "2022-04-23T11:42:38.911994851Z"
}

Network Internet Egress from Americas to Americas