Hey @kemmieg ,
Thanks for reaching out!
This is expected behavior. When you hide out-of-stock products in WooCommerce, they will be hidden from your shop results, but this doesn’t affect their SEO indexing. The product URLs remain intact and can be crawled and indexed by Google.
To prevent this, you may need to use an SEO-related plugin. If I’m not mistaken, I believe the Yoast SEO plugin allows you to set Noindex for Out-of-Stock Products and exclude them from your sitemap to prevent Google from indexing them.
Since support related to third-party plugins is outside our scope of support, you’ll need to reach out to the Yoast SEO plugin developers for further input on this. Here is a direct link to their dedicated support forum:
https://projectdmc.org/support/plugin/wordpress-seo/
Hope this helps point you in the right direction!