Google made an update to documentation about fixing search-related JavaScript problems. They added a new section and here it is:

*If you're using a JavaScript-based paywall, consider the implementation.*

Some JavaScript paywall solutions include the full content in the server response, then use JavaScript to hide it until subscription status is confirmed. This isn't a reliable way to limit access to the content. Make sure your paywall only provides the full content once the subscription status is confirmed.

In the update log they provide this reason:

*Why*: To help sites understand challenges with the JavaScript-based paywall design pattern, as it makes it difficult for Google to automatically determine which content is paywalled and which isn't.