Hubbard tapped her chest and made a heart gesture with her hands before leaving the competition floor.
"Thank you so very much for your interest in my humble sporting performance tonight,” Hubbard said afterward. "I know from a sporting perspective I did not live up to the standards I put upon myself."
Still, despite the early exit, Hubbard's performance was groundbreaking ... as the 43-year-old -- who transitioned 8 years ago -- became the first-ever transgender person to compete in the Games.
Of course, Hubbard's inclusion in the event did not come without controversy. As we previously reported, Hubbard had competed in men's weightlifting competitions before she transitioned, and critics called her inclusion unfair to other athletes.
"I know my participation in these games has not been entirely without controversy,” Hubbard said, before adding International Olympic Committee officials have "been extraordinarily supportive and I think that they have reaffirmed the principles of the Olympics that sport is something that all people around the world can do, that it is inclusive and successful."
The IOC, meanwhile, vowed on Sunday to unveil a new policy regarding the inclusion of transgender people in the Games following the Tokyo Olympics.