I picked a block that has a color picker on it, I putted a ring block or a boolean block in a color picker, and if I undo, the block has a empty input lol. If you want to save this empty input, put it in your backpack or duplicate it, delete the block you putted in your backpack or duplicated, get the block from the backpack that you putted in (not if you duplicated that), and it's a savable empty input!
Found this glitch. More empty input blocks: https://scratch.mit.edu/projects/572123811/
