Why Are Heirs Being Refunded?
The new skill enhancement system has changed the material requirements for Heirs. Specifically, there is a decrease in the amount of MolaGora required to enhance Hero skills. This has triggered a refund for the resources invested by Heirs prior to the change.

How Many MolaGora Will Be Refunded and How To Receive The Refund
The new skill enhancement system now treats 2-3★ Heroes differently than 4-5★ Heroes with regards to material investment, so refunded materials will be different for 2-3★ Heroes versus 4-5★ Heroes.
For a 2-3★ Hero the Heir must perform the “Reset Skill” function, which will be available on each 2-3★ Hero’s details screen (for Heroes enhanced prior to October 3 2019). Clicking the “Reset Skill” button will bring up a screen showing the Heir all resources that will be refunded to them if they complete the reset (which includes Catalysts, MolaGora, and Gold). If the Heir completes the reset the Hero will have all skill levels set to 0. The refunded materials will be placed directly into the Heir’s inventory once the “Reset Skill” selection has been completed.
For 4-5★ Heroes it will NOT be necessary to perform the “Reset Skill” function. The game developers have decreased the required amount of MolaGora for enhancement of skills for 4-5★ Heroes, therefore, any MolaGora or Gold spent by the Heir (before October 3rd) that was in excess of the new material requirements will be refunded to Heirs and will appear in their in-game mailbox under the GM tab. MolaGoraGo are also being refunded at a 1:4 exhange rate. Once this is completed (this requires no action from the Heir) refunded MolaGoraGo will appear in their in-game mailbox under the GM tab.