When you have a blank value, this plugin adds a blank id attribute. In the WYSIWYG, since you cannot see that, and since its invalid HTML (i think), I'd say it is a bug.
The plugin I found on gitlab, looks like it check for `null` but not an empty string. I think that all that needs to be tweaked.
Not sure how supported this module is, but since adding id attrs in CKEditor5 in Drupal is so hard, wanted to put this info out for anyone if they came across this.
Active
1.0
Code
Can't seem to reproduce this in the latest version.