[10.2 regression] CKEditor 5 prevents Styles from adding span as allowed HTML

There is a workaround but maybe undesirable to Add "Source editing" button
<span class>

Does it mean we cannot use span out of the box in CKE5 styles on Drupal 11 ?

The solution to this is to add the desired tags that are being disallowed to the Source Editing plugin. So you can just add into the Source editing plugin configuration field. The plugins that are enabled determines what tags will be allowed in the editor, and if it's complaining about any that it cannot allow, you just add them in the Source Editing plugin (the "allowed HTML tags" field is no longer editable).

Thanks for clarifying @wheelercreek

I’m exploring a potential solution by parsing the Styles plugin to dynamically add or update span elements. This would allow editors to define and manage styles more flexibly without creating a new plugin or allowing source editing workaround.

Would there be interest in pursuing this direction? Any thoughts or concerns?