The American world number four, who is Black, turned in an uncharacteristically listless performance in Beijing, double-faulting eight times as she went down 6-3, 6-3 to her Belgian opponent.
Gauff, 22, was playing a day after she called out the "insane" amount of abuse she had received on the internet following her win over Chinese teenager Sun Xinran in the previous round.
"It has been kind of draining. I'm not going to lie," Gauff said of the impact of the online comments.
"But I just turn off my phone and move on. There's nothing you can do."
Asked about the match, she said: "I think I just didn't play well. I think I wasn't moving well.
"There were a lot of things I didn't do well. I thought Elise played well on the bigger points."
During her previous match in Beijing, against Sun, Gauff requested a video review over flickering LED lights on the stadium's advertising hoardings.
The move prompted some boos from the crowd. The umpire agreed to have the point replayed, and Gauff went on to win 7-5, 6-1.
Early on Tuesday, Gauff wrote on X: "Hey everyone, you can dislike me or disagree about what happened without being racist."
She was responding to a post that contained a racial slur.
"The amount of racist comments and messages I've received in the last few hours is insane," she wrote.
Gauff also clarified that she challenged the point before Sun had returned the ball, when she noticed the lights flicker for a second time.
Neither the Women's Tennis Association - the global governing body - nor the China Open immediately responded to AFP requests for comment.