Pete from Laravel Support here!

Laravel Cloud doesn't support file uploads onto the container your application is hosted on. These containers can be replaced at any time for high availability reasons and as such, it's actually recommended you use an external Filesystem for your app.

If you create an Object Storage in Laravel Cloud and attach it to your cluster, you'll be able to adjust your code to save and retrieve files from there.

Here's the documentation: https://cloud.laravel.com/docs/resources/object-storage