How to filter by morph relation?

[MyLittleVerdant]

For an illustrative example. I have model AgreementPartner with fields entity_type, entity_id. I described morph relation with other models like this

In Models/AgreementPartner:

 public function partnerable(): MorphTo
    {
        return $this->morphTo(__FUNCTION__, 'entity_type', 'entity_id');
    }

In AgreementPartnerSchema i have:

 public function fields(): iterable
    {
        return [
            ID::make()->uuid(),
        
            Str::make('entityType'),
            Str::make('entityId'),

            MorphTo::make('partnerable')->types(CarrierSchema::type(), MerchantSchema::type()),
        ];
    }

  public function filters(): iterable
    {
        return [
            WhereIdIn::make($this)->delimiter(','),

            WhereHas::make($this, 'partnerable'),
        ];
    }

And in AgreementPartnerResource:

class AgreementPartnerResource extends JsonApiResource
{
    public function relationships($request): iterable
    {
        return [
            $this->relation('agreements'),
            $this->relation('partnerable'),
        ];
    }
}

It's works fine for
/agreement-partners?include=partnerable
but i can't do this
/agreement-partners?filter[partnerable][id]=01958f45-74ff-72af-9d72-6b081b485f9a

Although if I change the description of the relation in fields() to this

BelongsTo::make('partnerable')->type(CarrierSchema::type()),

Everything will work and even add filters filter[partnerable][] for all related resources, despite the fact that now only CarrierSchema is described.

But it's seems like bug for me. Is there any other option for filtering by morph relation?