Flakiness in tests can be a significant issue, as it not only wastes time but also reduces trust in test results. The root cause of flaky tests can hide in various layers of the system, making them difficult to detect and fix. One common mistake that leads to flakiness is using sleep() in tests, which should be replaced with waiting for a specific state change. Codecov's Test Analytics can help track and address flaky tests by providing detailed reports on test results, slowest tests, and average flake rate. By addressing flaky tests early, teams can maintain trust in their automated tests and avoid wasting time rerunning failed tests.