Frequent error logs on GCP API Gateway

Hi, I have an App Engine Standard Java 11 application served behind a GCP API Gateway. When I check the Cloud Logs I frequently see these errors like the following from API Gateway:

```
{
insertId: "5e1e0f456172eda03520c9fae065f312-1@a1"
jsonPayload: {
api: "//apigateway.googleapis.com/projects/abc/locations/global/apis/abc"
apiConfig: "//apigateway.googleapis.com/projects/abc/locations/global/apis/abc/configs/abc"
httpRequest: {
duration: "0ms"
hostname: "servicecontrol.googleapis.com"
httpVersion: "HTTP/1.1"
path: "/v1/services/abc.apigateway.abc.cloud.goog:report"
requestSize: "5003"
responseSize: "95"
status: 503
}
serviceConfig: "//servicemanagement.googleapis.com/services/abc.apigateway.abc.cloud.goog/configs/abc"
}
logName: "projects/abc/logs/apigateway.googleapis.com%2Fservice_control_queries"
receiveTimestamp: "2022-06-20T13:19:37.047238698Z"
resource: {
labels: {
gateway_id: "abc"
location: "us-central1"
resource_container: "projects/abc"
}
type: "apigateway.googleapis.com/Gateway"
}
severity: "ERROR"
timestamp: "2022-06-20T13:19:29.777308345Z"
}
```

What do these errors mean, should I be concerned?

Thank you