Intermittent Downtime in Rails Application Running on AWS App Runner

**Description**:
I'm experiencing intermittent downtime with my Rails application hosted on AWS App Runner. A third-party service, Crisp, monitors the availability of my site and sends notifications whenever it is unreachable. I receive these downtime alerts from Crisp a couple of times a day.

**Steps to reproduce**:
- Deploy a Rails application on AWS App Runner.
- Set up a monitoring service (e.g., Crisp) to check site availability.
- Observe the intermittent downtime notifications.

**Expected behavior**:
The application should remain available consistently, especially since there are no signs of high CPU or memory usage.

**Observed behavior**:
Even though the application is running under low load (as indicated by AWS App Runner metrics), Crisp reports that my site is unavailable for short periods. During these periods:

- Metrics show no CPU or memory exhaustion.
- However, AWS CloudWatch logs indicate gaps of up to 4 minutes between the last stream's end and the beginning of the next one, which aligns with the reported downtime.


**Questions**:
1. What could be causing these 4-minute gaps in the logs, which coincide with the periods when my site is unreachable?
2. Why might the Rails application be stopping so frequently, even when resource usage seems normal?

**Logs and metrics**:
I have attached relevant logs above and metric graphs below. Let me know if you need more details.