I saw this hat on a youtube video but the link to it wasn't posted. It's a top hat with a bow and a small rabbit peeking out.

This is from a conversion set from the game Shining Nikki called 灵魂魔术 (translates to "Soul Magic") by yaya-maya-sims on Tumblr and Patreon. Unfortunately, they deleted those accounts, taking all the download links with them. Luckily, I was able to find a SimsFileShare link of that set which was not deleted https://www.simfileshare.net/download/1437747/

Thank you!