Originally pointed out here: http://www.ocsmag.com/2017/03/29/discover-discover/ Screenshot: https://drive.google.com/open?id=0B_iE50uqUIIbdGpQOUpzZzJOZnM The margins separating an add-on's icon from the left edge of the surrounding box and the left edge of the description text are not always the same.
Fixed in commit https://phabricator.kde.org/R134:c057f37b6d4d2c8bcdbf33c1be2306dbb7d3e9b6