A chinese website by the name of Baidu Bar said that recently Korean fans are using the "silent-listening" method. They said Korean Cassiopeia had come up with the cheering for Mirotic a long long time ago but after the Mini Concert 2 different opinions surfaced: one is continue with the loud cheering while they sing, the other one is to use the "silent-listening" method like Japanese fans.
A lot of people agreed with the second opinion. Because DBSK said that this album is aimed for the public, if they keep cheering loudly while the boys sing the atmosphere will be good but it will have bad effect on other viewers.
After that Cassiopeia went and ask for an opinion from the boys themselves. The answer they received was that they hope the fans will listen to their performance silently. Because of that Korean fans have decided to follow the silent-listening method from then on.
The super loud cheering you heard from Mnet was because a lot of fans lost control that day (maybe because of the unexpected fan meeting??) and they said it really had bad effects on Tv's viewer. Korean fans dont want the same thing happen again so they carefully told everyone to keep quite during the Music Bank performance and even gave leaflets to every fan who came in that day.
Credit: Soompi & Baidu Bar