Forms\Components\Repeater::make('itemCategories')
  ->relationship()
  ->schema([
      Forms\Components\Select::make('category_id')
          ->label('Category')
          ->options(function ($state, Closure $get) {
              $selectedCategories = array_unique(array_column($get('../../itemCategories'), 'category_id'));
              $selectedCategories = array_map(fn($a): int => intval($a), $selectedCategories);
              $selectedCategories = array_filter($selectedCategories, function ($a) use ($state) {
                  return !($a === 0 || $a == $state);
              });
              return Category::query()->whereNotIn('id', $selectedCategories)->pluck('name', 'id');
          })
          ->required()
          ->reactive(),
  ])

Forms\Components\Repeater::make('itemCategories')
  ->relationship()
  ->schema([
      Forms\Components\Select::make('category_id')
          ->label('Category')
          ->options(function ($state, Closure $get) {
              $selectedCategories = array_unique(array_column($get('../../itemCategories'), 'category_id'));
              $selectedCategories = array_map(fn($a): int => intval($a), $selectedCategories);
              $selectedCategories = array_filter($selectedCategories, function ($a) use ($state) {
                  return !($a === 0 || $a == $state);
              });
              return Category::query()->whereNotIn('id', $selectedCategories)->pluck('name', 'id');
          })
          ->required()
          ->reactive(),
  ])