store-manage/app/Models/PlanHygiene.php

<?php

namespace App\Models;

use Illuminate\Database\Eloquent\Casts\Attribute;
use Illuminate\Database\Eloquent\Factories\HasFactory;
use Illuminate\Database\Eloquent\Model;
use Illuminate\Database\Eloquent\Relations\MorphOne;

class PlanHygiene extends Model
{
    use HasFactory;

    protected $fillable = [
        'month',
        'store_ids',
    ];

    public function plan(): MorphOne
    {
        return $this->morphOne(Plan::class, 'planable');
    }

    protected function storeIds(): Attribute
    {
        return Attribute::make(
            get: function (mixed $value) {
                if (! is_array($photos = json_decode($value ?? '', true))) {
                    $photos = [];
                }

                return $photos;
            },
            set: fn (mixed $value) => json_encode(is_array($value) ? $value : []),
        );
    }
}