Out-of-stock and SEO
When a product is temporarily unavailable, its page should remain indexed with an out_of_stock status in the Offer schema, a restock date if known, and an internal redirect to available alternatives, in order to preserve the URL’s accumulated authority.
In practice
Deleting a page for an out-of-stock product is a classic mistake: the URL loses its authority and backlinks, and Google must re-index a new page when stock returns. If the product is permanently discontinued, a 301 redirect to the parent category is the better option. Keeping the page live with its content and a clear availability message preserves rankings without misleading users.