Twenty subcontractors recently demanded better working conditions, but they were subsequently told to accept a counter-offer from their company or risk losing their jobs.
The situation has attracted attention from full-time employees, some of whom have been following thee dispute via the company's internal version of Facebook, known as Workplace.
Speaking to the Guardian newspaper on condition of anonymity, a Facebook software engineer said: "Threatening jobs on Christmas is really disgusting."
Earlier this month, 20 workers signed a letter to Filter Digital management in the hope of achieving better employment terms for themselves.
The letter read: "We have decided to be courageous and take change into our own hands by standing together in proposing changes to improve our working conditions.
"Many of us work second jobs, have subpar living arrangements, and/or cannot afford necessary medical care for ourselves and our families ... Many are simply one emergency away from possible homelessness. (sic)"
The letter pointed out that workers allied to other contractors already had better working conditions.