No it dose not cause screen burn it's amazing because samsung make the screen move ever few seconds so for example move the clock to the left slight and so on you would never notice it I have my always on with time date notices and fingerprint never had a problem. Hope this helps if you want to be sure enable it and watch your screen your see it move very slight around the screen to stop and prevent burn.
Having your brightness setting regularly high and screen timeout set at very long times... These contribute to screen burn. I also use dark mode regularly to help minimise risk of screen burn and to have battery life last longer. I've never had screen burn on any of my Samsung devices and I've had an awful lot of Samsung devices.