It appears that a palette created in version 14.3 cannot include control of magnification
The code:
CreatePalette[
Style["ABC",Bold,24]//Framed,
WindowSize->{100,60},
TextAlignment->Center,
WindowTitle->"Palette example",
WindowElements->{"MagnificationPopUp"}
]
Result in 14.2: 
Result in 14.3: 
