While the rest of Hyrule is suffering from the effects of gloom and various localized disasters, the current events in Hateno Village are comparatively lowkey in The Legend of Zelda: Tears of the Kingdom. After encountering the local fashionista Cece and witnessing a heated argument between her and Mayor Reede, a series of quests is set in motion.
One of these quests, Cece's Secret, deals with a rather obvious issue - finding out exactly what secret Cece could be hiding. Completion of this quest is required to finish off the events at Hateno Village, and it has a nice little reward at the end of it.
How To Complete Cece's Secret
Firstly, to start Cece's Secret, you'll have to first witness the argument between Cece and Mayor Reede by entering Cece's shop at the entrance to Hateno. After that, speak to Sophia when she's standing outside Cece's Shop.
Sophie will ask you to follow Cece when she leaves the shop at night, see where she goes, and find out what she's doing.
This is a simple quest, to begin with - wait until nighttime and approach Cece's shop. You'll spy Cece leaving the shop and walking across the street. Crouch (by pressing in the left analog stick) and get behind Cece, out of sight. Follow her slowly.
At some point, she'll stop in her tracks before looking around. When she does this, get behind the nearby pillar with mushrooms on it, on the opposite side to Cece. This will keep you out of her sight.
Cece will continue her journey across the street and up the steps around the silo next to the dye shop. After entering, she'll close the door, and you can't enter. You also cannot use Ascend from the well underneath Hateno as you can with Reede's version of this quest.
Instead, walk around the Silo's side and look up until you see a wooden platform. Use Ascend to reach the platform and then sneak into the silo through the small window. A cutscene will begin, showing you what Cece's secret actually is.
Return to Sophie and tell her the news. As a reward, you'll be given ten Ironshrooms, which are very useful ingredients. You'll also be one step closer to triggering the Mayoral Election.