In my 2D platformer, if my player hits the side of the top tile of the platform, they will just slide up on top of the platform.

When my player hits the side of a platform, they just slide up the side of the platform. Can anyone tell me why or how to fix this?

That’s probably occur because the way that you created your player colliders.

Try to watch this video from 5:40 and make the same 2d collider to your player.