A specific widget does not show data on some iOS 15.4.x devices

Hi, my App has two kind of widgets. On some iOS 15.4 and 15.4.1 devices, one widget works perfectly fine and another can't load data even in the Widgets Gallery. But for most devices the two widgets work both fine!!! My 15.4.1 iPhones and iPad can't reproduce the problem.

The problematic widget only display a redacted view:

The widget should look like:

Both of the widgets use Core Data to fetch data and shared UserDefaults to get user settings. The problematic widget is a task calendar, so it has some data but not very large.

I've try to collect crash log using TestFlight, but there's no crash logs.

I've implemented placeholder getSnapshot and getTimeline in the widget's IntentTimelineProvider. I'm not using unwrap optionals in SwiftUI.

It's frustrating. My users love this widget but can't use it. Any idea why this problem happen?