Abandoned Mine Land Reclamation Fee Reauthorization Act of 2021 This bill reduces the fee certain coal mining operations must pay to the Abandoned Mine Reclamation Fund, reauthorizes such fee through FY2028, and otherwise revises provisions regarding the fund and mine reclamation. Under the existing Abandoned Mine Land Reclamation Program, the Office of Surface Mining, Reclamation and Enforcement (OSMRE) collects a fee from coal mining companies for each ton of coal produced. The fees are deposited into the fund, which may be used to address hazards to public health, safety, and the environment from coal mining sites that were abandoned or unreclaimed as of August 3, 1977. For example, the fund may be used to provide grants to states and Indian tribes to reclaim and clean up land and water affected by such sites. OSMRE's authority to collect the fee expires on September 30, 2021. This bill extends the authority to collect the fee for seven years and reduces the fee for all categories of coal. It also provides additional grants for certain priority sites and revises requirements governing the distribution of grants to states and Indian tribes from the program. In addition, the bill allows states to (1) enter into a memorandum of understanding with relevant states or federal agencies to remediate mine drainage on abandoned mine land and water impacted by abandoned mines, and (2) partner with a community reclaimer who volunteers to carry out a reclamation project approved by the Department of the Interior.