From GameWatcher: “Team Fortress 2 Unusual items have broken the game’s economy. The new TF 2 Summer 2019 Cosmetic Case was supposed to add a dash of fresh air to the popular FPS, but ended up destroying its economy instead.
What happened is that players figured out a way to game the system and get guaranteed Unusual-tier items from the new crates. Given that there’s ordinarily just a 1% chance for an Unusual to drop, it’s clear as day that this is a major issue.”
Source: N4G PC Team Fortress 2 Economy Halted By Unusual Quality Cosmetic Items