I randomly found the solution online and here's the steps if you don't want the blur:
1. Download Goodlock App from galaxy store (the app is built by Samsung)
2. Open Goodlock app and choose "life up" at the bottom.
3. Find MultiStar and install it.
4. Open MultiStar. Scroll down to find "Remove blur effect on adjusting split view" and turn it on.
Hope you find it helpful!