There is an underlying assumption here. You seem to be running with the theme of making the review process more objective without considering the psychological aspects of being a human. As much as an employee’s productivity depends on how talented, hardworking, and skilled they are, it also depends upon how stress-free the environment is; with the conventional review process I had to worry only once per year of the “recency” bias, but with this I now have to constantly be on-guard about not upsetting anyone otherwise it will be a blackmark on my career. Plus the additional reckless usage that could happen as a result of anonymity and instant feedback. For eg. Think of a sick employee(who is not open abt their sickness) or a new joinee that is taking more time than usual to ramp up(within the probationary period) or any two employees with bad interpersonal relationships. This constant worry of who is thinking what abt me can make the office a pressure cooker of sorts.
Feedbacks are good. I am not saying they aren’t, but when you are designing a system that deals with organisational productivity I expect it to be a thoroughly designed system that covers most of flaws of the previous system if not all. It seems to me that by focusing only on recency bias and instant feedback, you are making way for more such people to run with a single idea without catering to the potential side-effects that could arise as a result of your implementation such as immense pressure of having to constantly put on mask for everyone around you, be on-guard 8 x 7. And as the saying in the medical field goes “even if you do no good, try to do no harm”, but I feel it(the anonymous + instant + peer review process) has multiplicative prospect of damaging the employee’s mental well being in the long run.