When you set the Key in Price field to "Must key in new price" and press the "Total discount amount" or the "Total discount %" button to give some discount, it's not applied, and no error or warning messages are displayed before you select the reason codes.
The changes in the hotfix add a flag to the "Retail parameters > Discounts" to enable the discounts for the items with keyed in price. When this flag is set, discounts will be applied with the keyed in price being true, else it won't apply the discounts.
The changes in the hotfix also make a few changes to how this happens for discount on price overrides.
This hotfix is a hybrid hotfix and also needs a kernel hotfix from DAXSE_3807361.