The bug
Selection boxes of options in some screens are offset in relationship to the text that is contained within them. These include:
Languages (2 px lower)
Statistics > General (2 px higher)
Statistics > Items (2 px higher; the box is also way longer than necessary)
Statistics > Mobs (2 px lower)
Resource packs: not really misaligned, but they don't shrink when they there's a scroll bar at the right (unlike the "Incompatible" red box), causing the right edge to become hidden.
Can confirm in 20w51a.