Propellerads traffic volums drop?

Today I saw a notification about volumes drop and the reason is strange. I ask the support and they told me the category of the campaign was change caused by landing content changed. The traffic will be lower than it used to be. They recommend me to re-launch it or change landings to old one. That was confuse me. We ususlly do A/B test for different types of landings to find out the better one, if it will cause the traffic drop, how do we test landings. Is there anyone has the same situation with me?