If you want to quickly check whether your AWS Lightsail usage is still covered by the new customer 90-day free benefit, here is the simplest way I use.
Step 1
Go to Billing and Cost Management.
Step 2

Go to Bills and click Expand All.
Step 3

Go check the Lightsail resource. The $0.00 per Hrs from 0 to 750 for BundleUsage:2GB in Asia Pacific (Singapore) will appear. $0 indicates your resource usage is under the new customer 90 days free benefit.
Alternatively, you can ask Amazon Q to help you query the data, or help you find it.