how to find out why Vulkan app crash on android?
What type of crash? CPU crash, or GPU DEVICE_LOST?
In general, making sure that the latest validation layer is not reporting errors is a good first step.
If you still get DEVICE_LOST after that, then bisecting by omitting parts of a frame, or using progress breadcrumbs, can help to narrow down what is crashing.
Hard to be more specific without more details of your problem.