This is a 100% completion (all stars and then some) list for the original 7 Scott Cawthon Five Nights at Freddy's games.

To unlock 4/20 mode in Five Nights at Freddy's 4 after finishing Night 7,

PC --- Visit the "Extra" menu and type "20202020" on your keyboard.

Xbox --- Visit the "Extra" menu, hover over "Nightmare", and press this button sequence: X-Y-X-Y-X-Y-X-Y.

PlayStation --- Same as Xbox, but press this button sequence: Square-Triangle-Square-Triangle-Square-Triangle-Square-Triangle.

Switch --- Same as Xbox, but press this button sequence: B-A-B-A-B-A-B-A

Mobile --- Visit the "Extra" menu, hover over the nightmare ANIMATRONIC, and tap until you unlock it.

Enjoy!