Convert String to Carbon

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Remove protected $dates = ['license_expire']

and then change your LicenseExpire accessor to:

public function getLicenseExpireAttribute($date)
{
    return Carbon::parse($date);
}

This way it will return a Carbon instance no matter what.
So for your form you would just have $employee->license_expire->format('Y-m-d') (or whatever format is required) and diffForHumans() should work on your home page as well.

If you’re using Laravel 9+, you can alternatively use the updated syntax for defining Accessors :

use Illuminate\Database\Eloquent\Casts\Attribute;

public function licenseExpire(): Attribute 
{
    return Attribute::make(
        get: fn ($value) => Carbon::parse($value);
    );
}