Google App Engine health checks spamming app

I've deployed a nodejs app running on the Google App Engine Flex runtime using the following app.yaml configuration:

runtime: nodejs
env: flex
health_check:
  enable_health_check: True
  check_interval_sec: 20
  timeout_sec: 4
  unhealthy_threshold: 2
  healthy_threshold: 2

According to the health check documentation the health checks should hit the /_ah/health endpoint every 20 seconds. However I noticed that my app is getting spammed with these health checks multiple times per second, even though the app responds with 200 status code.

Any idea why this is happening?

via Mihai Tomescu