Lambda environment variables disappear

Last week I noticed that all environment variables disappeared during the deployment using your action, but only for one application code. In other repositories, the same configuration works fine. Any idea what is going on?
I'm using the latest version and not setting any environment variables using the action. All environment variables are created earlier by Terraform.

No source files or tests are identified in the issue. Start by reproducing a deployment with the action for the affected application, then compare its Terraform-created environment variables with a repository where the same configuration works. Done means identifying why variables disappear for that application and confirming they persist after deployment.

Written by the indexing model from the issue text.