CloudNAT connection logging doesn't show post-NAT outgoing port number?

[jogu]

We are experiencing an issue where a client claims that some of our outgoing HTTPS connections aren't reaching their network, so have enabled cloud NAT logging. However the `nat_port` information in the logging does not seem to contain the after-NAT source port number that was used for the connect to the destination IP - and that information doesn't seem to be anywhere in the log.

e.g. in this example the `nat_port` is 900,  which clearly isn't the actual outgoing port as the documentation says CloudNAT will not use outgoing port numbers less than 1024, and checking the connection on the destination machine shows a different port number - one that is not present anywhere in the log message. Is this a bug in the logging or is there some way to map this port number to the actual one?

{
  "insertId": "17adxbyfg56ttg",
  "jsonPayload": {
...
    "connection": {
      "dest_ip": "18.229.116.174",
      "dest_port": 443,
      "src_port": 57836,
      "src_ip": "10.72.0.13",
      "nat_ip": "35.196.44.185",
      "protocol": 6,
      "nat_port": 900
    }
  },
  "resource": {
    "type": "nat_gateway"
  },
  "timestamp": "2024-02-07T10:27:20.729294750Z",
...
}