So is this suppose to lower everybodys hashrate so to bring difficulty down

Some people are saying this bricks their antminer. So if you don't have the firmware saved before upgrading it this could be the case.
for the ones having issues, they may not have the compatible version of S9 - there are ones with specific C5 control boards that are not compatible.
They can always reinstall the prior version by downloading and updating to the old one.