icon_circle_box's perfectly-circular StyleBoxFlat (corner radius equal
to half the box size, no straight edges between corners) is a known
Godot degenerate case that draws a faint seam through the middle when
antialiasing is on and looks faceted at low corner_detail. Bumping
corner_detail and disabling antialiasing renders a clean circle at
these small badge/icon sizes instead - affects every icon_circle_box
call site (answer badges, stat tiles, avatars, etc.), not just the
question player.
hz