In Detail

public function allowedFilters(): AllowedFilterList
{
    return Filter::only(
        Filter::field('name', [FilterType::EQUAL]),
    );
}

public function allowedFilters(): AllowedFilterList
{
    return Filter::only(
        Filter::relation('comments', [FilterType::HAS],
            Filter::only(
                Filter::field('content', [FilterType::LIKE])
            )
        )
    );
}

public function allowedFilters(): AllowedFilterList
{
    return Filter::only(
        Filter::morphRelation('imageable', [FilterType::HAS_MORPH],
            Filter::morphType('*', Filter::only(
                Filter::field('created_at', [FilterType::LESS_THAN_EQUAL_TO])
            )),
        )
    );
}

Filter::morphType('*', Filter::only(
    Filter::field('created_at', [FilterType::LESS_THAN_EQUAL_TO])
)),

Relation::morphMap([
    'foodService' => FoodDeliveryService::class,
]);

class Subscription extends Model implements IsFilterable
{
    use Filterable;

    // ...

    public function allowedFilters(): AllowedFilterList
    {
        return Filter::only(
            Filter::morphRelation('subscribable', [FilterType::HAS_MORPH],
                Filter::morphType(FoodDeliveryService::class, Filter::only(
                    Filter::field('price', [FilterType::EQUALS])
                )),
                Filter::morphType(Saas::class, Filter::only(
                    Filter::field('plan', [FilterType::EQUALS])
                )),
            )
        );
    }
}

Subscription::filter([
    [
        'target' => 'subscribable',
        'type'   => '$hasMorph',
        'types'  => [
            [
                'type'  => 'foodService', // Custom morphMap alias from Relation::morphMap().
                'value' => [
                    [
                        'target' => 'price',
                        'type'   => '$eq',
                        'value'  => 9.99,
                    ],
                ],
            ],
            [
                'type'  => 'saas', // Model database table due to Saas::class not being in the Relation::morphMap().
                'value' => [
                    [
                        'target' => 'plan',
                        'type'   => '$eq',
                        'value'  => 'basic',
                    ],
                ],
            ],
        ],
    ],
])

Filter::morphType(Target::alias('foodService', 'food_delivery_services'), Filter::only(
    Filter::field('price', [FilterType::EQUALS])
)),
Filter::morphType(Target::alias('software', 'saas'), Filter::only(
    Filter::field('plan', [FilterType::EQUALS])
)),

public function allowedFilters(): AllowedFilterList
{
    return Filter::only(
        Filter::custom('$latest')
    );
}