When Huawei Mate40 Pro uses Alibaba APP, the message reminder sound is not the built-in dingdong. It may be due to the following reasons:

1. Application settings: Alibaba APP itself provides a variety of notification sounds. You can choose your favorite sound as a notification reminder in the application settings. By default, the application may use the default notification sound provided by the system.

2. System settings: The default notification sound available in the Huawei Mate40 Pro mobile phone system may be dingdong, but in actual use, some users may prefer the sound provided by Alibaba APP itself.

3. Personalization: Users can customize the notification sound in the phone settings according to their preferences. You can choose your favorite music, sound effects or system-built-in sounds as reminder sounds.

4. Software version: There may be certain differences between different versions of Alibaba APP, which may lead to different sound settings. You can try to update the application to the latest version to see if it can solve the problem.

5. System version: The system version of Huawei Mate40 Pro may also affect the settings of notification sounds. You can try to check the system settings of your phone to see if there are relevant options to adjust.

In short, when Huawei Mate40 Pro uses Alibaba APP, the message reminder sound is not the built-in Dingdong. This may be due to the combined effect of multiple factors such as application settings, system settings, personalization, software version and system version. You can adjust it in the relevant settings according to your needs to achieve satisfactory results.