I'll crib the intro from Wikipedia:
Latinx is a gender-neutral English neologism, sometimes used to refer to people of Latin American cultural or ethnic identity in the United States.
"Latinx" is a somewhat controversial term, as WP continues:
Surveys of Hispanic and Latino Americans have found that most prefer other terms such as Hispanic and Latina/Latino to describe themselves, and that only 2 to 3 percent use Latinx. A 2020 Pew Research Center survey found that roughly three-quarters of U.S. Latinos were not aware of the term Latinx; of those who were, 33% said it should be used to describe their racial or ethnic group, while 65% said it should not.
The citations in the article refer to popular press articles, based mostly on surveys and Pew research, which I don't generally have a problem with, but I'm looking for research by linguists on "Latinx" (and more broadly the related terms "Latine" and "Chicanx") among US residents and non-US residents.