They helped to organize an unprecedented global protest that saw tens of thousands of Google employees walk off the job in November 2018. Now two Google employees, Meredith Whittaker and Claire Stapleton, are alleging that Google is retaliating against them and other employee activists.

“Google has a culture of retaliation, which too often works to silence women, people of color, and gender minorities,” reads a letter from Whittaker, Stapleton and 10 other employees that was published internally on Monday and seen by the Guardian.

“Retaliation isn’t always obvious. It’s often confusing and drawn out, consisting of icy conversations, gaslighting, project cancellations, transition rejections, or demotions. Behavior that tells someone the problem isn’t that they stood up to the company, it’s that they’re not good enough and don’t belong.”

Stapleton, a nearly 12-year veteran at Google, wrote that two months after the walkout, she was demoted, had a previously approved project cancelled, and was “told to go on medical leave, even though I’m not sick”.

“Only after I hired a lawyer and had her contact Google did management conduct an investigation and walked back my demotion, at least on paper,” she wrote. “While my work has been restored, the environment remains hostile and I consider quitting nearly every day.”

Whittaker, who co-founded the AI Now Institute, wrote that after Google decided to scrap its AI ethics council, she was told that her “role would be changed dramatically”. “I’m told that to remain at the company, I will have to abandon my work on AI ethics and the AI Now Institute,” she wrote.

Neither Whittaker nor Stapleton responded immediately to a request for comment. The letter was first reported by Wired.

A Google spokeswoman said that the company has already investigated these cases and determined there was no retaliation.

“We prohibit retaliation in the workplace, and investigate all allegations,” the spokeswoman said in a statement. “Employees and teams are regularly and commonly given new assignments, or reorganized, to keep pace with evolving business needs. There has been no retaliation here.”

Google employees have been at the forefront of a wave of tech worker activism that has swept the industry over the past year. Employee-organized protests have taken aim both at the company’s business decisions – such as its work for a Department of Defense drone project or plans to build a censored search engine for China – and its treatment of employees and contractors.

The November walkout was sparked by a New York Times report that revealed that a former executive, Andy Rubin, had received a $90m severance package despite being forced out over an allegation that he had forced a female employee to perform oral sex. The report unleashed a flood of anger and frustration among Google employees who had faced harassment or discrimination.

In Monday’s letter, the organizers say that they “collected over 350 stories” during the walkout, and discovered a “sad pattern”: “People who stand up and report discrimination, abuse, and unethical conduct are punished, sidelined, and pushed out. Perpetrators often go unimpeded, or are even rewarded.”

The organizers are planning to host a Retaliation Town Hall for workers on Friday. They have reserved conference rooms and plan to live stream the discussion internally.