In WP 5.4.x, I was able to add a number to the URL for any page, post, etc. (incl. custom post types), which WP interpreted as the 'page' for a multi-page post, even if that page or post didn't actually have multiple pages. I assume that this was some kind of shortcut for /page/12345/

I could, for instance, open /some-page/12345/, even if that page didn't use a "nextpage" tag. The behaviour also worked for custom post types, e.g. WooCommerce products.

I used this behaviour in a custom plug-in where I needed a numeric ID passed (without having to use custom rewrites). In WP 5.5, WP does a 301 redirect via redirect_canonical instead when a post/page doesn't actually have multiple pages. Is there a way to restore that old behaviour in 5.5?