https://backpack.tf/item/15606064340

Going by this it most likely wasn't unusualified:

https://backpack.tf/profiles/76561199487791471#!/compare/1744934400/1745712000

https://backpack.tf/item/15119397116

Wasn't unusualified:

https://backpack.tf/profiles/76561199565022108#!/compare/1744416000/1744588800

https://backpack.tf/profiles/76561199183892084#!/compare/1744502400/1744588800

Bot to bot? Must have been bought then instantly dumped to STN:

https://backpack.tf/profiles/76561199183892084#!/compare/1745366400/1745452800

https://backpack.tf/profiles/76561199026390261#!/compare/1745366400/1745452800

The 9 keys and 11.33 ref line up with the current seller on Marketplace.tf:

https://backpack.tf/profiles/76561199026390261#!/compare/1746144000/1746230400

https://imgur.com/fKWhS3W

Rounding to 9

https://backpack.tf/item/15103697071

Dumped to a bot, nothing matches:

https://backpack.tf/profiles/76561198121456056#!/compare/1743897600/1743984000

https://backpack.tf/profiles/76561199102237820#!/compare/1743811200/1743897600

Slobek owns the Yes bot so the sale between them and the bot is a transfer. It then sold on marketplace.tf.

Marketplace.tf sales: https://marketplace.tf/items/tf2/31466;5;u3001

April 17: $24.99/1.91=13.08 ~13 keys

May 23: $24.99/1.92=13.02 ~13 keys

https://steamcommunity.com/market/listings/440/Unusual%20Taunt%3A%20Peace%20Out?filter=Showstopper

None for sale on SCM currently

Going with 9-13 keys