@JI_Gravityworks We're trying to evaluate this module vs Group Content Menu. I would love to see your work if you have a repo somewhere.
Reroll for 10.1
Wim Leers → credited ericras → .
I don't think there is an issue with Drupal. I think this is a limitation with CKEditor5 itself.
In Drupal and on the CKEditor demo page, it works with block level elements ("Block styles") as you would expect. If you set a rule for blockquote.my-style|My Blockquote Style it will only be allowed on blockquote elements.
However, with "Text styles" it allows them anywhere AND it creates the element where it didn't exist before. On the CKEditor demo https://ckeditor.com/docs/ckeditor5/latest/features/style.html they have a rule span.spoiler|Spoiler which can be added anywhere, not just to existing span elements, and it will create the span tag. It works the same way with an "a" tag rule: it can be created anywhere and the "a" tag will be added. This is unfortunate.
I haven't been able to find an issue in the CKEditor project which references this behavior/limitation/bug.
10.1.x update