For a project folder structure like:

repo
|--- packages
| |--- host-app => `ember deploy production` will be run in here
| |--- addon-1
| +--- addon-2
+--- node_modules/.bin/netlify

The deploy plugin is expecting the node_modules to be under host-app folder due to this line. Perhaps, workspaces/monorepos create the node_modules at the root of the repo.

The plugin should detect if it is run from a workspace configured ember app and if so, not expect it to have the node_modules but the root one.

One possible solution I could think of is to use npx based commands for this same LoC and prevent the need for a devDependency of netlify.