There are several free competitors: Doodim, Hocus Focus, Backdrop, and Isolator, DeskCover.
Copypast - the author took the idea from Izolator or from other free alternatives that appeared earlier and implemented HazeOver
Sadly, even if I tried the app for a week, I couldn't change my habit of "CMD + tab". So much faster.
I'm sure some people will like the app. But not me sorry ! 😐
This has been a standard app on my machine. It is one of those utilities that does its work day in and day out making my experience a much more pleasant one. I have wrestled from time to time with how strong to set the opaqueness of my Haze in order to give me a good workspace. I have also not toyed much with changing the color of the haze, but expect this could make for a fresh workspace, if needed.