For @ManyToMany associations, the REMOVE entity state transition doesn't make sense to be cascaded because it will propagate beyond the link table.

Checks for @ManyToMany associations with the CascadeType.REMOVE attribute. Specifying CascadeType.REMOVE for @ManyToMany doesn’t make sense to be cascaded because it will propagate beyond the link table. Since the other side might be referenced by other entities on the parent-side, the automatic removal might end up in a ConstraintViolationException. For example, if @ManyToMany(cascade = CascadeType.ALL) was defined, and the first person would be deleted, Hibernate would throw an exception because another person is still associated with the address that’s being deleted. For more info see the article.