Why my AWS Lightsail instance for WordPress site using Lightsail blueprint keeps getting stopped

Hello.

What are the specs of your Lightsail instance?
WordPress blueprints that do not use Bitnami will also set up applications other than WordPress, such as phpMyAdmin.
Therefore, it is possible that it may be more susceptible to load than Bitnami WordPress.
So, try starting an instance with specs one level larger than the ones you were using for Bitnami WordPress and see if the same problem occurs.
https://docs.aws.amazon.com/lightsail/latest/userguide/compare-options-choose-lightsail-instance-image.html#compare-cms-applications

It may be easier to understand if you compare the CPU usage of the instances.
Your Lightsail instance may be consuming burst credits.
https://docs.aws.amazon.com/lightsail/latest/userguide/monitoring-cpu-burst-capacity.html

Hello, Checkout this Similar issue

https://repost.aws/questions/QUMKlYvYYjQCOlHqts8Gkisw/wordpress-lightsail-instance-keeps-crashing-even-with-very-little-traffic

Hi,

Please contact AWS Support under the free support plan to get the issue looked into.

Thanks.