Rewarding Efforts to Decrease Unrecycled Contaminants in Ecosystems Act of 2021 or the REDUCE Act of 2021 This bill imposes an excise tax on any taxable virgin plastic resin. The bill establishes a Plastic Waste Reduction Fund to carry out reduction and recycling activities, plastic waste and marine debris reduction, detection, monitoring, and cleanup activities, and address environmental justice and pollution impacts from plastic products.