Migration from gomoob/php-pushwoosh [possible regression]

[TheUnableDeveloper]

Hello,
I just migrated my project from gomoob/php-pushwoosh,
What I did was basically removing the old library from composer.json and then I added the new one.

Everything works Except something in this file:
src/main/php/Gomoob/Pushwoosh/Model/Notification/IOS.php

public function jsonSerialize(): mixed
    {
        $json = [];

        isset($this->apnsTrimContent) ? $json['apns_trim_content'] = intval($this->apnsTrimContent) : false;
        isset($this->badges) ? $json['ios_badges'] = $this->badges : false;
        isset($this->categoryId) ? $json['ios_category_id'] = $this->categoryId : false;
        isset($this->rootParams) ? $json['ios_root_params'] = $this->rootParams : false;
        isset($this->sound) ? $json['ios_sound'] = $this->sound : false;
        isset($this->ttl) ? $json['ios_ttl'] = $this->ttl : false;
        isset($this->trimContent) ? $json['ios_trim_content'] = intval($this->trimContent) : false;

        if ($this->threadId !== null) { // <--- EXCEPTION ----------
            $json['ios_thread_id'] = $this->threadId;
        }

        return $json;

    }

Exception:
"Typed property Gomoob\Pushwoosh\Model\Notification\IOS::$threadId must not be accessed before initialization", line 124

this is the contenct of my $json variable

two questions:

1. Is it the proper way to migrate the one I described?
2. Is this exception generated by the library OR by my code?

Thanks!

Versions:
PHP: 8.2.25
Library: 2.1.0

[TheUnableDeveloper]

Small update:
I tried the library version 2.0.0 and everything works fine, so I guess it's a regression