Due to a feature, a user was allowed to override an approved edit, which resulted in their question getting tagged with the untagged tag. That should not be allowed, given that no question should be untagged (unless it was migrated from another site or had all of its tags burninated), and the untagged tag is prevented from normally being applied as it is blocked network-wide.
Therefore, that feature should check if overriding a suggested edit will cause the question to use blocked tags, and if so, it should reject the override attempt.
Alternatively, in this situation the rollback could only revert the content of the post and not the tags.