You were most likely phished. Read more about it here. - https://marketplace.tf/blog/posts/YHLZOB
- Uncropped and Unedited screenshots of your complete chat on the steam client with the user who led you to this trade offer
If you don't have un-cropped versions find them here on this page https://help.steampowered.com/en/accountdata/GetFriendMessagesLog
- Please find them on a web browser and hover your mouse over the username of the account in at least one of the pictures, so we can see the URL at the bottom left corner of the screen.
Example- should look like this https://imgur.com/a/ImcDuhP
- Screenshot of the trade offer - should also be Uncropped and Unedited, also in a web browse, with mouse your hovering over the username so that profile URL pops up in bottom corner.