Knives should never go in the dishwasher. Dishwasher detergent is very abrasive, along with the banging around that happens during a wash cycle so that it will take the sharp edge right off your knife.
Furthermore, The water jets in the dishwasher can cause the blade to knock into whatever else you have it in the dishwasher with and can damage the edge.
Then there are the detergents, which can be just as dangerous as the machine itself, causing the knives to dull or discolor, so that’s why cutters may go blunt in the dishwasher, so you must prevent the blades from putting into the dishwasher; otherwise they may get blunt.