`REST_REQUEST` is defined after `plugins_loaded`.

The plugin runs the following on the `plugins_loaded` hook to determine if the site is making a rest request.

```php
// Don't redirect REST API requests
if ( defined( 'REST_REQUEST' ) && REST_REQUEST ) {
return;
}
```

Unfortunately, `REST_REQUEST` is only defined after the plugins have loaded so after the code above is passed.

Moving the redirect to the `send_headers` action works around this.

Start by locating the plugin code that checks REST_REQUEST on the plugins_loaded hook and trace how the redirect is registered. Verify the behavior for a REST request, then confirm that moving the redirect to send_headers prevents REST API requests from being redirected.

Written by the indexing model from the issue text.