Contractors at Google and other tech companies are typically treated and managed as real employees except for minor legal-motivated things like travel which is treated differently.

Further, contracts are typically for a fixed period of time.

That these employees/contractors seemed genuinely surprised by the abrupt termination suggests this was not the natural end of their contract. Google, not Cognizant, decides when their contracts end. If their contracts were terminated with no warning or reason given, it was initiated by Google. And with that background it seems pretty likely it was in retaliation to the union activity.

“But they’re not Google employees”, right? But then, that’s why Google and other tech companies use contractors - to avoid giving those employees actual employee protections.