Unlike Button and Checkbox, setting enabled to False on a ToggleButton doesn't grey out the text. This is visually disturbing amongst other disabled controls. I suspect this may be an Android, rather than a B4A, quirk and can be overcome by setting the TextColor to a suitable value.
This is not a bug in B4A. It is how the standard ToggleButton behaves. I wouldn't use ToggleButton at all but it should be simple to modify its colors.
Check B4XSwitch from XUI Views for a much nicer control.