What problems can arise when parallelizing tests?

Race conditions when accessing shared resources. Deadlocks between threads or processes. Tests depending on each other, leading to unpredictable results. Difficulty debugging parallel tests. Increased resource consumption (CPU, memory). Need for synchronization of data and resource access. Problems with test execution order. Complexity in setting up test environments for parallel execution. Increased complexity in writing and maintaining parallel tests. Incorrect formation of test execution reports.