Gracefull shutdown doesn't work for processes started from user data script on ec2

Steps to reproduce

1. I started an EC2 instance with a user data script.
2. This script initiates my application.
3. A graceful shutdown is implemented in the application (an HTTP request is sent upon receiving SIGTERM).
4. I stop/reboot/terminate the EC2 instance. Expected: The application receives a SIGTERM signal and makes a request. Actual: The application does not receive any SIGTERM signal.

It seems like processes started from the user data script do not receive a SIGTERM signal on system shutdown.

What I've tried:

1. Starting the process in the foreground (python3 /app.py).
2. Starting the process in the background (python3 /app.py &).
3. Starting the process in the background with nohup (nohup python3 /app.py > /dev/null 2>&1 &). None of these methods work.

What worked:

1. Starting the process in the background via SSH (ssh <ec2 instance> 'nohup python3 /app.py > /dev/null 2>&1 &').