I really am enjoying using Mojave despite the fact some of my Apps have not been updated to take full advantage of it’s features. Like any other macOS, you have to set it up the way it works best for you. In line with that sentiment, the feature “Recent Items” which shows in the Dock is just not necessary for me. It is one of the first things I changed after installing Mojave. Here is how to turn it off if it bugs you also.