That's because you closed the exercise of Alipay.
1. Open the settings in the phone desktop.
2. In Settings, click Permissions and Privacy.
3. In Permissions and Privacy, click Rights Management.
4. On the rights management page, click Alipay.
5. On the Alipay page, click Fitness.
6. In the pop-up box, click Allow.
After this setting, you can take several steps on WeChat Alipay.