Not meritocratic

Amazon is not as meritocratic as most people, especially new hires, imagine. People are frequently praised for building a shiny thing or stopping a fire. They are rarely praised for preventing a fire or a security issue or doing the hard work that it takes to keep an old system running. A lot can depend on being on the right team at the right time.

On top of that, expectations can be arbitrarily high and may be increased based on previous successful reviews. Essentially you end up competing against your previous self and your colleagues, but this is not discussed openly by management until they decide to get rid of you and can justify it by saying you're not growing.