This hat finally got sold after about 2 years of being in a collector's backpack. Only 1 sale was able to happen as the other gym rat of the same effect is not being traded rn.

Sale:

Seller: https://backpack.tf/profiles/76561198218063977#!/compare/1633996800/1634169600

Buyer's backpack doesn't seem to be updating to show the items sale.

Picture of sale: https://imgur.com/a/g6NY6Hq

I will post the buyer's proof once it updates!

Buyer: https://backpack.tf/profiles/76561198256998558#!/compare/1634083200/1634256000

Seems like they bought another hat that day so there's a lot more keys removed.