Meta also does something like 5% in unregretted attrition a year. I just don't know why you think AMZN wouldn't include those people in layoffs preferentially to higher performers.
During my time at Meta, they were teaching the engineers a lot, spent a lot of effort on proper onboarding, allowed changing teams at least once a year (more often with longer tenure), and otherwise seemed to make it easier for an engineer to find a better place in the Meta's structure instead of leaving.