You can choose which issue types are considered "Unplanned" by adding them to the "Defect work types" field in the PM Configuration.
In CodeScene's vocabulary, "Unplanned work" refers to work that is not part of planned feature development. A bugfix prompted by a report from a customer is unplanned, from this point of view. On the other hand, if you have a tag/work type which means additional, unanticipated work that is necessary for completing a feature, we would tend to consider that as "Planned work", because it is still part of a planned feature.