Humidity Indicator Cards indicate excessive moisture with a visible color change from blue to pink. When the packing bag is open, this card can be examined for proper dryness inside a bag. If there is a color change, baking might be required prior to the reflow process in order to remove any moisture out of the plastic package. For the baking condition, it depends on the packing thickness, MSL level and your baking temperature.
See also:
Humidity Indicator Cards
https://forum.digikey.com/t/ipc-jedec-j-std-033b-dry-packaging/7426
https://www.digikey.com/en/pdf/s/scs/scs-jedec-jstd033b-standards