How to find a specific steam community market user?

There is profile name history, however it can be cleared and then shows "This user has no known aliases".

steamid.uk can sometimes give you historic profile info, but I don't think you can find a profile by a previous name. You would need to suspect a user and look up there account to see if it lists their old name as Cat Ramen.

I originally was gonna suggest backpack.tf to check your inventory history and item history, but 1)I'm not sure how far back bp.tf goes and 2)it appears item history has been wiped couple years ago. You can still try that first tho. Go back to your inventory date of when you still had the hat, click history and check its current owner.
I also did some searching around and found a website(http://www.tf2items.com/) that takes your inventory snapshot periodically(idk how often tho my last one was 2020, then 2019). Clicking on an item will give you the info and more importantly the ID of said item, and then you can append the id after bp.tf history link(https://backpack.tf/item/XXXXXXX for example) to find said item.