The last Unity version had redesigned piece icons. Those are back, as a Steam exclusive. Steam owners now have two choices for piece icons. The o.g. icons from early release, and the most recent redesigned icons! Select your icons in the settings menu.
Source: Steam Community (opens in a new tab)
Build and release context
Steam update times within 24 hours of this post. Matching dates do not confirm which build it describes.
Build 25939995 · public branch
Steam updated · First observed