When rendering with Blender on AWS Deadline Cloud, AVI files are being generated for each frame.

Based on the information available, there's no indication that AWS Deadline Cloud generates AVI files for each frame when rendering with Blender.

When rendering a Blender scene on AWS Deadline Cloud, the service processes the job and produces rendered frames according to the output settings configured in your Blender project. The rendered frames are typically stored in Amazon S3 as job attachments, and you can download these rendered frames once the job is complete using the Deadline Cloud Monitor application.

AWS Deadline Cloud has recently added a feature that automates job attachments output downloads, making it easier to synchronize rendered assets back to your workstation. This feature allows you to automatically download completed job outputs from S3 to local paths that you specified during job creation.

If you're seeing AVI files generated for each frame, this is likely due to your specific Blender output settings rather than a default behavior of AWS Deadline Cloud. You may want to check your Blender project settings to adjust the output format if needed.
Sources
How to render a Blender scene on AWS Deadline Cloud | AWS for M&E Blog
What's New at AWS - Cloud Innovation & News

The Deadline Cloud Blender integration doesn't currently support generating a movie automatically from a sequence of frames and renders each frame as an individual task. This is why you're seeing each task generate a single frame avi when the output format is set to avi. If you change the output format to PNG, or other image format, the render will generate individual frames that can be combined into a movie using ffmpeg or other tools.