It's common to get a second vesting in your third year (or else your comp would go down). It's almost common to get a promotion around that time -- managers are responsible for promoting their employees, and it's taken seriously.
It also means your destiny is in your manager's hands, which can be unfair if you end up with a bad manager, or several new ones. And unfortunately at Amazon, this is very common (current employee here).
That's literally every job ever. You aren't going to have a successful career at Google if your manager doesn't want you to. The org golden handcuffs are gone, so if you have a bad manager, change teams.
For the record "bad managers" are no more common or less common at Amazon as any other company.