Litigation Funding Transparency Act of 2021 This bill requires lawyers for plaintiffs in certain lawsuits to provide the court and other parties in the lawsuit with any agreement that entitles an outside business (i.e., a business that is not a party, class member, or counsel in the lawsuit) to receive payment contingent on the lawsuit's outcome. The lawyers for the plaintiffs shall also provide the identity of the outside business. Specifically, these requirements shall apply to any class action or multi-district litigation (i.e. related civil cases pending in different districts that are consolidated for pretrial proceedings).