SOCD Cleaner is a function that allows you to switch the behavior when the controller's direction key buttons are pressed in opposite directions at the same time.
The switching method is different for each board: RP2040 model, PUNK WORKSHOP original chip (PKB) model, and Brook model, so please refer to the one that matches your board.
RP2040 model
PKB model
About the SOCD (simultaneous input in opposite directions) cleaner switching function of PKB model
Brook model
About the Brook model's SOCD (simultaneous input in opposite directions) cleaner switching function