Using base64 encoded absolute URLs as part of config is not a good security practice.
For more information on how to setup launch configurations, see the AWS documentation.
In Terraform -
References:
https://docs.aws.amazon.com/autoscaling/ec2/userguide/create-asg-launch-configuration.html
https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/launch_configuration