How to solve "The payload is invalid" in Laravel 8 when the payload suddenly becomes NULL

I keep getting this error when trying to decrypt a password previously encrypted:

The payload is invalid.

And this is the relevant stack trace:

#0 /home/improojf/public_html/vendor/laravel/framework/src/Illuminate/Encryption/Encrypter.php(136): Illuminate\Encryption\Encrypter->getJsonPayload(NULL)
#1 /home/improojf/public_html/vendor/laravel/framework/src/Illuminate/Encryption/Encrypter.php(164): Illuminate\Encryption\Encrypter->decrypt('eyJpdiI6InloT0U...', false)
#2 /home/improojf/public_html/vendor/laravel/framework/src/Illuminate/Support/Facades/Facade.php(261): Illuminate\Encryption\Encrypter->decryptString('eyJpdiI6InloT0U...')
#3 /home/improojf/public_html/app/Models/Server.php(29): Illuminate\Support\Facades\Facade::__callStatic('decryptString', Array)
#4 /home/improojf/public_html/vendor/laravel/framework/src/Illuminate/Database/Eloquent/Concerns/HasAttributes.php(473): Server->getPasswordAttribute('eyJpdiI6InloT0U...')

The biggest issue here is that a string randomly becomes NULL in the encrypter code, which makes no sense to me.

Another issue with this, is that some records just behave ad intended.

What do I use it for This is used to store passwords for smtp/pop3 servers on a database

What I tried This problem is perfectly solved by not encrypting/decrypting the password, which messes up the purpose

Does it always return error? No, in fact there are some records that behave normally

What are my guesses php artisan cache:clear might be an option as reported elsewhere, but I think there should be another solution. So far I have (untested) the following accessor while previously I only had the second try/catch

public function getPasswordAttribute($value){
    try {
        return Crypt::decryptString($value);
    } catch (\Illuminate\Contracts\Encryption\DecryptException $e) {
        \Illuminate\Support\Facades\Artisan::call('cache:clear');
    }
    try {
        return Crypt::decryptString($value);
    } catch (\Illuminate\Contracts\Encryption\DecryptException $e) {
        if(app()->runningUnitTests())
            return $value;
        else
            throw $e;
       }
}