When using Peonia, do I have to randomize my Prize cards after putting them back?
Rearranging the prize cards is not part of Peonia's effect, so wherever you put the new prize card is where it should stay until some other action causes the prize cards to be rearranged.
Source: Chilling Reign FAQ; TPCi Rules Team (2021-06-17)

Relevant cards

Note: All applicable cards may not be listed below.
SWSH6_149
SWSH6_149