Marijuana Opportunity Reinvestment and Expungement Act of 2021 or the MORE Act of 2021 This bill decriminalizes marijuana. Specifically, it removes marijuana from the list of scheduled substances under the Controlled Substances Act and eliminates criminal penalties for an individual who manufactures, distributes, or possesses marijuana. The bill also makes other changes, including the following: replaces statutory references to marijuana and marihuana with cannabis, requires the Bureau of Labor Statistics to regularly publish demographic data on cannabis business owners and employees, establishes a trust fund to support various programs and services for individuals and businesses in communities impacted by the war on drugs, imposes an excise tax on cannabis products produced in or imported into the United States and an occupational tax on cannabis production facilities and export warehouses, makes Small Business Administration loans and services available to entities that are cannabis-related legitimate businesses or service providers, prohibits the denial of federal public benefits to a person on the basis of certain cannabis-related conduct or convictions, prohibits the denial of benefits and protections under immigration laws on the basis of a cannabis-related event (e.g., conduct or a conviction), establishes a process to expunge convictions and conduct sentencing review hearings related to federal cannabis offenses, and directs the Government Accountability Office to study the societal impact of cannabis legalization.