If I add a label like
on the source code side of CKEditor, it appears well on the WYSIWYG side. But if I go back to the source side and go back to the WYSIWYG side, it has been transformed as:
So, I tried to disable Advanced content filter when unchecking "Limit the allowed HTML tags and correct the defective HTML code" and also using the
hook_ckeditor_plugin_info_alter, according to this answer.
I also tried to add
allowedContent = true using ckeditor_config.
Unfortunately without any results.
How to disable this filtering, at least for