When using the Content Lock module with CKEditor4, it disables the text editor interface (but not the toolbar buttons). When switching to CKEditor5 the Content Lock module does not seem to disable the editor. Even when the content is locked, the user can still interact with the a CKEditor5 text area.
CKEditor5 includes a Restricted Editing Mode, which the Content Lock module could take advantage of. This mode allows for disabling the editor (including toolbar buttons).
See the CKEditor5 docs on Restricted Editing Mode for more details and demos/examples of how the editor behaves in this mode.
Restricted Editing | CKEditor5 Documentation
Closed: duplicate
2.0
User interface
Since this issue was created, 🐛 Ckeditor field not getting disabled on locked form RTBC was created and already has a patch.