After uninstalling I was still getting the same error.
I had a look at the source code, turns out the check is quite fragile:
try {
sassImplementation = require('node-sass');
wco.logger.warn(`'node-sass' usage is deprecated and will be removed in a future major version. ` +
`To opt-out of the deprecated behaviour and start using 'sass' uninstall 'node-sass'.`);
}
Which means that, if you have node-sass installed globally, or in a parent directory somewhere, you'll get this warning.
To test this, make a new file in your project directory and run it with node:
const t = require('node-sass');
console.log(t);
If you don't get module_not_found, it means it's node_sass is being resolved.
In my case I had node-sass installed under my user home directory.