On nodes that have had a field, eg body, with a value created in CKEditor 4, we are now seeing "Activating CKEditor 5 will reformat the content of this field. Review content carefully after activating. Click to activate editor." which is scaring some of the users...yeh, I know...

How can I fix every piece of content so that this is not an issue any longer?

Looking at the database source of the node_revisions, I couldn't see any difference between CK4 and CK5 versions, so it must be set in another table or json file?