Disaster Learning and Life Saving Act of 2020 This bill establishes within the executive branch a National Disaster Safety Board to study the underlying causes of disaster-related fatalities and property damage nationwide and make policy recommendations, and authorizes appropriations for the board through FY2024. Specifically, the board shall review and establish the facts, circumstances, and cause or probable cause of the loss of life, human injury, and economic injury due to a natural hazard or public health incident with 10 or more fatalities. The board shall initiate a review of an incident by monitoring the situation and assessing available facts to determine the appropriate review response without interfering in any ongoing lifesaving and life sustaining efforts underway by other entities; disseminate best practices for the development of internal review organizations; and establish an office to review and make recommendations to mitigate and prevent the loss of life, or human or economic injury, for vulnerable populations. The Government Accountability Office shall audit the board at least once every two years.