The term transracial originated within the adoption community to describe parents of one race / ethnicity adopting children of a different race / ethnicity.
Folks like Rachel Dolezal co-opted the term and twisted it into a new meaning (Rachel Dolezal, after unsuccessfully suing historically black college Howard University in 2002 for discriminating against her as a white woman, later claimed to be black, even darkening her skin and getting perms to align her appearance with a fictional black identity). Unfortunately, her controversial story and others such as Oli London (a white British man who claimed to be Korean due to his obsession with K-Pop star Jimin, who underwent dozens of surgical procedures in his quest to look like his Asian idol), have caused the term transracial to have a rather negative connotation.
Nowadays, some adoptees opt to use the term interracial instead of or in addition to the term transracial. Arguably, interracial is a more accurate term to describe racially / ethnically mixed families.
However, personally I prefer the term transracial not only out of principle, but because I feel it more accurately describes the complete and total assimilation of a non-biological ethnicity / racial viewpoint that adoptees in these situations often go through due to complete cultural immersion and lived experience due to their family upbringing (with no choice in the matter). This experience is reflected in FORK MOUNTAIN.