Problem/Motivation
If CKEditor 5 is selected as text editor for the Basic HTML format then the "Language" button is added automatically to the toolbar. This is also the case, if the text editor is switched from a CKEditor configuration where the Language button is disabled. (I suppose that would be a regression.)
For the other default text formats (Full and Restricted HTML), the Language button is not automatically added.
The Language button has very limited use in a Drupal site because content languages are organized through the Core modules, and the user experience can be really confusing if HTML markup for languages can also be added within a field. Therefore enabling the Language button should be a concisous choice of a sitebuilder, not the default option.
Steps to reproduce
- Enable the CKEditor 5 module
- Go to the configuration of Basic HTML at /admin/config/content/formats/manage/basic_html
- Change the text editor from "CKEditor" te "CKEditor 5"
Proposed resolution
Do not add the Language button to the default CKEditor 5 toolbar configuration for Basic HTML.