My sidebar widgets are visible before unlocking a protected category
WooCommerce Protected Categories only protects the main content area of a product or category page. It does not protect global content such as sidebar widgets, which appear on multiple pages.
If you have unticked the ‘Show protected categories & products in public-facing store’ box in WooCommerce → Settings → Products → Protected Categories then your protected content will not appear in any WooCommerce-specific widgets such as the Products or Categories widgets. However, the widgets themselves will still appear before unlocking the category.
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