Foreign Agent Disclaimer Enhancement Act of 2021 or the FADE Act of 2021 This bill revises the disclaimer requirements for informational materials transmitted by agents of foreign principals. Specifically, the bill requires that, when such an agent posts information in support of a foreign principal on an online platform, the agent must ensure that the information includes the required disclaimer (i.e., a statement that the information is being transmitted by such an agent). Further, the bill specifies that the disclaimer requirement applies to an agent whether the agent is within or outside the United States. Upon notification by the Department of Justice (DOJ), an online platform must remove any materials that do not meet disclaimer requirements and must use reasonable efforts to inform recipients of the materials that they were disseminated by an agent on behalf of a foreign principal. DOJ must analyze and report on the legal, policy, and procedural challenges to effective enforcement of foreign agent registration requirements.