Trying to fix PHPStan Issues with Laravel's MorphTo relations and Model properties

We recently started using PHPStan 1.10 at level 6 in a Laravel 10 PHP 8.2 project.
It reports a few remaining issues in the following model that I would like to fix.

class ArticlePrice extends Model
{

    protected $fillable = ['cost_type_id', 'type', 'type_id', 'amount'];

    /**
     * @var array<string> $with
     */
    protected $with = ['types'];

    /**
     * @return MorphTo
     */
    public function types(): MorphTo
    {
        return $this->morphTo('types', 'type', 'type_id');
    }

    /**
     * @return string
     */
    public function getName(): string
    {
        if ($this->types) {
            return $this->type === Article::class ? $this->types->vdm_code : $this->types->name;
        }

        return '';
    }
}

For the types() MorphTo it reports:

phpstan: Method AppModelsEnvironmentCostTypeArticlePrice::types() 
return type with generic class IlluminateDatabaseEloquentRelationsMorphTo 
does not specify its types: TRelatedModel, TChildModel

But if I change it into MorphTo<Model, Article|Category> which reflects the actually models it could return at this point it complains about:

phpstan: Method AppModelsEnvironmentCostTypeArticlePrice::types() should return
 IlluminateDatabaseEloquentRelationsMorphTo<IlluminateDatabaseEloquentModel,
 AppModelsShopArticle|AppModelsShopCategory> 
but returns IlluminateDatabaseEloquentRelationsMorphTo<IlluminateDatabaseEloquentModel,
 AppModelsEnvironmentCostTypeArticlePrice>.

which is weird to me, since we are in ArticlePrice, this seems nonsensical to me.
It has the exact same complaint when I do <Model, Model> instead.

The other issue is that it does not understand the content of $types:

phpstan: Access to an undefined property IlluminateDatabaseEloquentModel::$name.
phpstan: Access to an undefined property IlluminateDatabaseEloquentModel::$vdm_code.

I hoped fixing the morphTo issue would fix this as well, since vdm_code and name are documented properties of their models. But I fear this would not work, so this might need a different way of fixing the issue.

In short, how can I get PHPStan to understand how my polymorphic relation works, and how do I get it to recognise properties of the polymorphic related models?