Plugin CKEditor outputs something with nothing?
This has been fixed in the master branch, but not yet tagged in a release: https://github.com/craftcms/ckeditor/pull/6

Until it's tagged, you won't be able to get that fix in from the Plugin Store, but you can pull it in with Composer in the command line if you want.

FWIW, it's currently a pretty minimal beta version of the plugin using an older dev preview version of CKEditor 5, so I wouldn't rely on it too heavily until it gets updated.