In December 2019 – shortly before the start of the pandemic – Korean Air announced a huge devaluation of their frequent flyer program with revenue-based mileage-earning and a new distance-based award chart coming in April 2021.
Korean Air has offered one of the more lucrative frequent flyer programs for many years, and access to outstanding award inventory not made available to its partners. However they’re also part of a joint venture with (and partially owned by) Delta, so devaluation of their mileage program was almost a given – at least until the pandemic hit.