If you go from Google or similarly large company to a small startup, there's a radically different reality and workstyle required. Any time I see someone with big company experience especially their immediately previous role, it's an orange flag. I know to dig into why a startup and whether they are willing to "repent" their previous ways.
BigCo employees are much more likely to call unnecessary whole team meetings, unnecessarily drag out feature planning, drag their feet on getting MVPs out in favor of a entirely complete solution, propose doing things "the way <x> does it" and it's like "... cool, we don't have the resources and headcount to support that really."
With that said, generally these people have a much deeper knowledge of their particular stack, are valuable to have as long as you can harness them correctly and direct their energies towards much later in the startup.
I guess the problem for affected soon-Xooglers is more like, they've been laid off hence could be seen as underperformers. Moreover, they hit the marketplace in quantities, which makes for a bad negotiation position. Also, I'm wondering if top talent at Google not laid off this time around might soon look elsewhere and leave the sinking ship before it's too late - after all, Google hasn't really diversified despite lots and lots of investment and it's not clear at all top coders are really needed to keep a maturing business going (or are actually still working on eg Search or other key tech considering its demise) over the last 5+ years).
What about former Microsoft employees? Amazon employees?
Is big tech an ethical issue for you? Or is it just Google?