It's almost always easier to get a new job, when you still have one.
Plus, being an ex-FAANG is a huge bonus when applying for jobs at "normal" places or starts ups.
YMMV on this one, depending on what you consider "normal" companies (non-tech, non-coastal, non-advertising).
Plenty of those hiring managers have their own opinions about FAANG employees
Some people are being laid off for performance. Most are being laid off because they were unlucky.
Hiring managers don't have time to be super sleuths. If your interview and reference process can't weed people out, then you shouldn't be in charge of hiring people. Either way, the person who gets laid off from Amazon is going to have already shown the capacity to jump through a dozen stupid hoops by sheer process of being offered a job to work there.
"Need to explore other opportunities" is a little weaker but still works.
"This chapter in my life is over" is also popular.
I think I should make a bingo card out of these.