The message you are seeing may or may not be related to cheaters you reported. The message is just saying that you have played with currently-banned players, and it has reverted any MMR gain or loss you've had from any of the recently banned players. The rollback is the total amount of MMR impacted - both positively and negatively. By losing MMR from the system, this means you gained more MMR from banned players vs losing against them.
For more info on the system, we have a dev blog here.
This thread was added on April 20, 2020, with posts from UbiMorning.
Original Post
i got a message about hackers i have reported and actually they were hackers so the game instead of giving me my mmr back they decreased my mmr so what is this game i am supposed to get plat 1 but i got deranked to plat 3 any fix new developer team??