On my macbook pro, this extension show unnormal
Thanks for reporting! I’ll take a look at it.
@Sunderlandkyl there may be issues with ctk groupbox in dark mode (see also Some widgets not updating appropriately on style change · Issue #5135 · Slicer/Slicer · GitHub).
@canoe_ccrg until the problem is fixed you can change from automatic (Slicer) to fixed light or dark mode (Light Slicer or Dark Slicer) in menu: Edit → Application settings → Appearance → Style.