The film 'A Year-End Medley, 2021' does not feature any identifiable LGBTQ+ characters or themes. The narrative focuses on various interconnected romantic and interpersonal relationships among an ensemble cast, all of which are depicted as heterosexual.

There is insufficient information available regarding the film's plot or characters to determine if transsexual individuals or themes are present, or to evaluate their portrayal. Without specific details on any relevant character arcs or story plots, a comprehensive assessment of the net impact cannot be made.

The movie does not contain any action or adventure elements.

The film "A Year-End Medley" is an original production with no indicated prior source material, historical figures, or legacy characters. Therefore, no characters are established as a different gender in previous canon or history.

The film is a South Korean production featuring a South Korean cast. No information is provided regarding pre-existing source material or historical figures that would establish a character's race prior to this film's creation. Therefore, no race swaps can be identified.