If so, that’s just an indicator telling you can add something there. It doesn’t add a block or render anything.
If you’re pertaining to the “Type / to choose a block”, that’s an empty paragraph block. Make sure you remove those because that will render an empty space.
You can use Block editor’s “List view” and set the editor view to ‘Top Toolbar’ so you can remove selected empty paragraph blocks as shown here – https://share.getcloudapp.com/xQu6lxNo