Huawei Technologies’ overtime culture is biting back. An open letter has been posted to Huawei’s internal messaging board — and then quickly deleted — containing a sharp rebuke of the company’s overtime policy and alleging executives are covering up the full extent of extra work that’s happening.

Authored by Hu Ling, a member of the human resources team at Huawei’s elite 2012 Lab research unit, the document reflected dissatisfaction and distrust developing within the Chinese tech giant’s ranks.

“Take my advice brothers: don’t trust HR, they have no honesty,” Hu wrote in the letter posted on Wednesday evening, according to a screenshot. The note also questioned the efficiency of engineers working long overtime sessions. The post could not be accessed as of Friday morning. Its authenticity has been confirmed by Huawei, which declined to comment further on the matter.

Part of its self-described “wolf culture”, Huawei’s embrace of long working hours was this summer kicked into high gear by the imposition of US sanctions as part of a broader trade war with China. It led to 24-hour work days, with engineering teams working in shifts around the clock to come up with alternatives to American tech and suppliers. The company took steps in July to reward employees for accelerating revenue despite the US ban, but Hu claims months of heavy overtime are starting to take their toll. Overtime is common among Chinese tech companies, though the relentless work culture is starting to receive stronger push-back.

Huawei’s messaging board was electrified by the post, with some other employees speaking up in support. “The real force that takes down the company isn’t from outside but from within,” one employee wrote on the forum, expressing disappointment at the company’s increasingly exposed internal issues. Inside Huawei’s campuses in Shenzhen and Shanghai, canteens and shuttle buses run until midnight to accommodate employees who work late.