Project P.I.T.T. Panel Rack
The official 1.0.5 and 1.0.6 Panel Rack changes: multi-panel carrying, a dedicated keybind, and deliberate dispensing behavior.
The Panel Rack was added in Update 1.0.5 as a multi-level upgrade for carrying more than one panel. In 1.0.6 it gained its own keybind and only dispenses another panel when pressed again.

1.0.5: carrying multiple panels
The official 1.0.5 notes describe Panel Rack as a new upgrade with multiple levels to carry more than one panel at a time. The notes do not publish its price, exact tiers or unlock condition.
1.0.6: dedicated use behavior
The official 1.0.6 notes say Panel Rack has its own keybind and will not automatically dispense another panel. Press its control again when another panel is needed.
Unknown unlock condition
DEFERRED — EVIDENCE INSUFFICIENT. Community theories about when or how the Rack appears are not presented as official progression data.
Primary source: Official Steam news — Updates 1.0.5 and 1.0.6 ↗. Scope: full game.