Lightsall facing start instance

Hello.

Does the IAM user trying to launch Lightsail have an IAM policy attached to operate Lightsail?
Also, have you checked the troubleshooting document below?
The documentation includes information such as trying to operate as root user and updating the browser.
https://docs.aws.amazon.com/lightsail/latest/userguide/create-policy-that-grants-access-to-amazon-lightsail.html

You can sign in as the root user of your AWS account by following the steps in the document below.
For security reasons, it is not recommended to use the root user for daily operations, so please use it for this troubleshooting purpose.
https://docs.aws.amazon.com/signin/latest/userguide/introduction-to-root-user-sign-in-tutorial.html

If the troubleshooting above does not resolve your issue, as described in the documentation, please contact AWS Support.
In this case, I think you should open a case under "Account and billing".
Inquiries under "Account and billing" can be made free of charge.
https://docs.aws.amazon.com/awssupport/latest/user/case-management.html

Hi,

You should have received communication from AWS about the issues with your account. Email correspondence from AWS are sent to the email address on the account and/or visible in AWS Support Center. Please follow the instructions from that communication. The general instructions can also be found here.

After completing those steps, respond to the notification in the AWS Support Center with a confirmation that you have completed the required steps.

If you haven't received such communication please contact AWS Support under the free support plan using the Accounts category and describe your issue.

Thanks.