Does the system change from before?
because I saw a lot of hacks in the last round after the contest finished and even after the new rating changed !!
Does that mean that the rating will occur temporarily and you will wait for some time for hacks to happen for regular rounds(because the system before was you can hack for 12 or 24 hours in specific rounds like educational or div3 or so) before the final rating occurs?
For regular div2 rounds nothing changes, I guess. If your solution gets hacked, you don't lose any rating.