Some even characterised the internal culture at Facebook as "cult-like," according to the report.
"There's a real culture of 'Even if you are f---ing miserable, you need to act like you love this place,'" one former employee who left in October told CNBC. "It is not OK to act like this is not the best place to work."
The former employees put much of the blame on Facebook's twice-yearly peer-review system, in which each employee was typically given feedback by five of their colleagues.
The system made employees feel the need to participate in after-hours social events, grab lunch with teammates, and remain a positive advocate for the company to remain in good standing with colleagues, according to the report.
"It's a little bit of a popularity contest," one of the former employees said. "You can cherry-pick the people who like you - maybe throw in one bad apple to equalise it."
Once peer feedback is collected, employees are "stack-ranked" and assigned a grade by management. Only a certain percentage of employees can receive each grade, so managers must advocate for their direct reports to receive the highest honors, according to the report.
"There's a saying at Facebook that once you have one bad half, you're destined for bad halves the rest of your time there. That stigma will follow you," one former manager told CNBC.
The stack-rank system was introduced by management guru and General Electric CEO Jack Welch in the 1990s and adopted by Microsoft until 2013 when the company stopped the practice amid a declining employee morale.
Read the full CNBC report here.
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