requiredWithoutAll() doesn't seem to be working

<?php

namespace App\Filament\Pages;

use App\Filament\Pages\Concerns\HasProfileSerializationAction;
use Filament\Forms\Components\TextInput;
use Filament\Pages\Page;
use Filament\Schemas\Concerns\InteractsWithSchemas;
use Filament\Schemas\Contracts\HasSchemas;
use Filament\Schemas\Schema;
use Livewire\Attributes\Url;

class VetProfile extends Page implements HasSchemas
{
    use InteractsWithSchemas;
    use HasProfileSerializationAction;

    #[Url]
    public ?int $memberId = null;

    protected string $view = 'filament.pages.vet-profile';

    public function form(Schema $schema): Schema
    {
        return $schema
            ->components([
                TextInput::make('a')
                    ->requiredWithoutAll('b'),
                TextInput::make('b'),
            ]);
    }

    public function save()  {
        // do nothing
    }
}