If your goal is more defensive than the past performance of your account or campaign, it is normal that Adspert will lower the bids to meet your new goal.
In general, a very defensive target will result in lower bids, resulting in a decreasing number of impressions and clicks. Therefore, the cost per conversion and the number of possible conversion decrease. It is also possible that some more expensive campaigns will be scaled back as a result of the new objective in order to save costs and achieve the overall objective.