I am not sure that these figures are new, and the article doesn't present them very well.
About 48,000 patients underwent such surgeries during the five years studied, with about 13,000 procedures done in 2019, the peak year, and 12,800 in 2020.
A little more than half the patients were ages 19 to 30. Surgeries in patients 18 and younger, were rare: fewer than 1,200 in the highest volume year.
Among the youngest patients, the most common surgeries were breast and chest procedures, with more than 3,000 young people undergoing such operations during the five-year period.
These were likely transgender males — generally high school graduates — having their breasts removed, said Dr. Loren Schechter of Rush University Medical Center in Chicago, who specializes in gender-affirming surgery and was not involved in the study. Having breast surgery at that age allows them to “go to the next phase of their life in a body with which they’re comfortable and is synchronous with their identity," he said.
The gender identities of the patients were unclear in the data and couldn't be inferred in categories like breast reconstruction, which could be for either transgender males or females.
Private insurance covered most patients who had such surgeries, the researchers found. About 1 in 4 patients received coverage through Medicaid, the federal-state health care insurance program that helps pay for health care for low-income people.
https://www.independent.co.uk/news/jason-wright-ap-medicaid-obama-columbia-university-b2398073.html
Have now found original article. Seems quite long but maybe more informative https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2808707