I have the same issue as @IoannisTzon. I did all that @avaddon suggested. Synapse was able to recognize devices. All seemed fine until I move my mouse around. WindowServer goes over 100% CPU usage, making my entire system lag like hell. When I launch World of Warcraft, the frame rates are terrible. It’s completely unplayable. When I unplug razer devices and use Magic Mouse it works like a charm and WindowServer doesn’t go above 20%. Please help. What must I do?

I completely uninstalled Razer, removed 'R2H967U7J8' from consent list restarted, and still have the problem. Computer lags badly in games, WindowServer usage is over 130% whenever I move the mouse around. Problem completely disappears as soon as I use the Magic Mouse. So can't do anything until Razer software works natively on the mac or Big Sur is changed to allow 1000Hz polling rate:(