Documentation for cke5 suggestgs cke4 plugin

This does seem to be the case. It’s worth noting that the CKE4 div plugin worked with CKE5 for quite a while right up to Drupal 11.1.8.

Drupal 11.2 included a version bump to CKE5 that moved the icons into a new location. When a page attempts to load CKE with the div manager controls visible, the browser throws an error and the CKEditor UI doesn’t load at all.

I’ve had to remove the module from a site entirely as it was blocking publishing work, but you could potentially roll your own by patching it to source a custom version of @ckeditor/div:4.x that looks for the icons in the new location…