Lindsey McNeil and her 7-year-old daughter, Noelle, who suffers from cerebral palsy and epilepsy, were jolted by an alert they received from Florida’s Department of Children and Families late last month that Noelle would be losing her Medicaid coverage 10 days later.

Their lives have since begun to unravel, Ms. McNeil said. Noelle has stopped seeing the four therapists she visits each week and is running low on medications she needs to prevent her seizures from flaring up. Monday brought a measure of relief: Ms. McNeil learned that Noelle’s coverage had been temporarily reinstated as they wait for a resolution to an appeal filed with the state.

“We’ve worked really hard to grow our family and our life and a home for this child,” Ms. McNeil said. “It’s a little daunting to think about what she may lose, and what we may not be able to provide for her.”

Noelle was one of the most recent casualties of the unwinding of a pandemic-era federal policy that required states to keep people on Medicaid, the health insurance program that covers low-income Americans, in exchange for more federal funding. While the policy was in place, enrollees were spared regular eligibility checks. Enrollment in Medicaid and the Children’s Health Insurance Program swelled to a record of more than 90 million, and the nation’s uninsured rate dropped to record lows.

But the policy lapsed at the start of April last year, allowing states to resume trimming their rolls, and the so-called unwinding process that ensued has had far-reaching effects. More than 20 million Americans lost Medicaid at some point in the past year, according to KFF, a nonprofit health policy research group — an unprecedented event in the joint federal-state program’s nearly 60-year history.