I’m not sure what you’re referring to. Would you please provide a screenshot of what you’re seeing?
https://ww.wp.xz.cn/support/forum-user-guide/block-editor/#adding-screenshots
The default post meta box leaves a lot to be desired from a user experience standpoint. The ACF fields end up saving post meta the same way as the default meta box, but ACF gives you more flexibility in how it’s presented and integrated into the editor. ACF fields can be added to other types of data which don’t have default meta boxes.
IMO the only advantage of the default meta box is it’s built-in and no additional plugin is needed. If it’s good enough for your needs, you might not want to add an extra plugin.
