cssd-back/app/Models/Transfer.php

<?php

namespace App\Models;

use Illuminate\Database\Eloquent\Model;
use Illuminate\Database\Eloquent\Relations\BelongsTo;
use Illuminate\Database\Eloquent\Relations\MorphTo;
use Illuminate\Database\Eloquent\SoftDeletes;

class Transfer extends Model
{
    use SoftDeletes;

    public $fillable = ['user_id', 'to_date', 'from_date', 'status', 'user_transfer_id'];

    public function user(): BelongsTo
    {
        return $this->belongsTo(User::class);
    }

    public function userTransfer(): BelongsTo
    {
        return $this->belongsTo(User::class, 'user_transfer_id');
    }

    public function transferable(): MorphTo
    {
        return $this->morphTo();
    }
}