Is the Zalo app causing the AirPods 2 battery to drop to 0%?

I am in Vietnam and using Google Translate, so please bear with me.
Here is the situation: I sold a pair of AirPods that I had been using without issues to a customer, but after taking them home and using them, the customer reported the following:
- They work perfectly fine for listening to music and making video calls via Messenger, and the battery performance is completely normal.
- However, when using the Zalo app to make calls, the battery drops to 0%.
- Has anyone ever encountered this issue? Is there really a third-party app that can cause AirPods 2 to suddenly fail? Thank you!