yeah its some painful legacy CSS.
In the earlier versions of the theme there wasn’t the same level of control to resize archive featured images. And generally there is not enough space for the image to be aligned to the side when posts are displayed in columns. So the decision was made to disable floating images in columns and mobile. Reversing that CSS now could effect a lot of existing sites.
We are looking at other blog layout options for the future. But for the time being its simplest to resolve with CSS