[QUESTION]升级版本后, 无法解析出以前redis中已存的带有@type的key

### 请描述您的问题
*询问有关本项目的使用和其他方面的相关问题。*

The report concerns fastjson2 deserialization of existing Redis data containing @type after an upgrade. Start by reproducing the failure with the stored value and comparing behavior before and after the upgrade. Done means identifying the compatibility cause and confirming a documented or tested way to parse the existing data.

Written by the indexing model from the issue text.