Usually cook your food in one layer unless the recipe states that stacking is ok (like in these air fryer French fries and sweet potato fries recipes) I believe this may aid quite a bit with the crumbs slipping down. Although some will often fall (that’s usual), in this way https://airfryer11086.pointblog.net/the-smart-trick-of-air-fryer-that-nobody-is-discussing-71871150