Claire Stapleton, an employee at Google's YouTube who spearheaded employee-led policy change movements, has left the company after 12 years, claiming retaliation by company leaders.

"The heads of my department branded me with a kind of scarlet letter that makes it difficult to do my job or find another one," Stapleton wrote in a note shared on Medium on Friday morning. "If I stayed, I didn't just worry that there'd be more public flogging, shunning, and stress, I expected it."

Stapleton, a YouTube marketing manager, confirmed with CNBC that she quit on Wednesday. Her departure comes as some Google employees claim they have faced retaliation for questioning the company's handling of policies spanning anti-harassment to equal rights for contractors.

Stapleton was one of seven Google employees who organized a massive protest, called the Google Walkout for Real Change, in which 20,000 Google employees and contractors in 50 cities walked off campuses last November to protest the company's handling of sexual harassment cases. That resulted in Google changing some of its policies, including ending forced arbitration.

Stapleton claimed that while Google publicly praised her and the organizers' work, it was a different story internally, alleging managers retaliated against her and a fellow Walkout organizer. Stapleton said at the time that she was demoted and told to take medical leave even though she wasn't ill.

Walkout organizers again questioned the company's public branding this week when YouTube flip-flopped its enforcement of anti-harassment policies for a far-right user who regularly featured homophobic and racial slurs, all while claiming to support LGBTQ employees for Gay Pride Month. Stapleton left that day, though it isn't clear whether the incident had a direct bearing on her departure.

"I hope that leadership listens," Stapleton continued in her Medium post. "Because if they won't lead, we will."

Google said in a statement, "We thank Claire for her work at Google and wish her all the best. To reiterate, we don't tolerate retaliation. Our employee relations team did a thorough investigation of her claims and found no evidence of retaliation. They found that Claire's management team supported her contributions to our workplace, including awarding her their team Culture Award for her role in the Walkout."

WATCH NOW: Google employees protest the company's harassment policies.