I had used cinnamon in Linux mint but that was long ago so I could be wrong. I think you need to change the icon theme which you can find in appearance in system settings. There you will find four options Mouse Pointer,Applications,Icons,Desktop. You should be able to select the theme you want and if you don’t find the mint icons then install the mint-y-icons,mint-y-theme package using dnf install mint-y-icons mint-y-theme, then set the mint theme for applications, icons and desktop. I think by default linux mint uses the mint y aqua theme which will included with mint-y-theme. Give it a try and see if it helps.