Announcement reposted from Amazon Japan:
Starting December 11, we will require all Deals to include a validated reference price to improve customers’ Deals experience. This change will affect all types of Deals including but not limited to Top Deals, Best Deals, Lightning Deals, and Prime Exclusive Deals (Prime Exclusive Top Deals, Prime Exclusive Best Deals, and Prime Exclusive Lightning Deals). After December 11, all Deals ASINs without a reference price (List Price and Was Price) will be suppressed.
The validation rule will impact all Deals that run on and after 00:00, December 11, 2023.
For all Deals, we recommend you review the reference price (List Price and Was Price) on your offers as a reference point of your Deals price setting.
There will be no notification for the suppression. After December 11, the validation system will run during an event and non-event period and this include all sales events.
Additional resources on managing Deals: