This is due to a new feature introduced in Odoo 18. While Odoo 17's Snippet Library provided various drag-and-drop options, it lacked advanced preview capabilities and keyword-based selection.

In contrast, Odoo 18 introduces over 60 new snippets and substantial improvements to the snippet selection process. Users can now view live previews of snippets before adding them, making it easier to select the appropriate one. The addition of a keyword-based discovery system further streamlines snippet selection. Moreover, users can seamlessly replace a dropped snippet with another, enhancing flexibility and efficiency.

To learn more about the new features in Odoo 18, please refer to the blog below:

https://www.cybrosys.com/blog/odoo-18-v-s-odoo-17-key-features-and-release-notes-of-odoo-18

Hope it helps