End Taxpayer Funding of Gender Experimentation Act of 2021 This bill modifies provisions relating to federal funding for, and health insurance coverage of, gender reassignment medical interventions, which include surgical remedies and hormone therapy arising from a conflict between an individual's gender identity and the sex the individual has or was identified as having at birth. Specifically, the bill prohibits the use of federal funds for gender reassignment medical interventions or for health coverage that includes such interventions. Additionally, such interventions may not be provided in a federal health care facility or by a federal employee. Under current law, coverage of these interventions through Medicare and Medicaid is generally determined at the state level. The bill's restrictions regarding the use of federal funds do not apply to treatment of individuals with medically verifiable disorders of sex development, such as individuals born with atypical development of chromosomal, gonadal, or anatomical sex. The bill also prohibits qualified health plans from including coverage for gender reassignment medical interventions. Further, plans that include coverage for such interventions are not eligible for federal subsidies.