I am getting JEST test environment was torn error message. I am not sure why that is happening. Any pointers or suggestions which I could try to solve this issue? Is it possible to debug such issue?

Hard to tell with limited details here and I haven't used Jest since couple years. But did you try clearing cache? https://stackoverflow.com/questions/44866994/how-can-i-clear-the-jest-cache Does it also happen with a fresh project clone & npm install?

Actaully I am testing functional component using react testing library and test is very simple just DOM testing but in beforeAll block there is jest.FakeTimers() will that cause this problem?