Banning Microtargeted Political Ads Act of 2021 This bill generally prohibits online platforms (e.g., websites, mobile applications, and social networks) from disseminating political advertisements that are targeted to an individual, a connected device, or a group of individuals or connected devices based on personal information that is linked to an individual or device. The prohibition does not apply to a political advertisement that is targeted to (1) an individual or device within a recognized place (e.g., states, Indian lands, and congressional districts), (2) an individual who gives express consent for the political advertisement, (3) an individual who is searching for the information, or (4) an individual on a random basis. Additionally, the bill establishes a private right of action with respect to the prohibition. Further, pre-dispute arbitration agreements and pre-dispute joint-action waivers are unenforceable with respect to a dispute arising from the prohibition. The bill expands the definition of electioneering communication to include certain internet or digital communication that is placed or promoted on an online platform for a fee and also expands the exception to this definition for news. Further, it broadens the definition of public communication to include a communication by means of any paid internet, paid digital communication, or paid promotion.