We are here revisiting the need to use the analog switch voltage booster. This is needed in some families, if analog features (e.g. ADC) are used. However, it appears that signal speed is not the only reason to use the analog booster.
As reported in this thread, if VDDA<2.4V, (while VDD is presumably at around 3.0V or higher), and the analog switch voltage booster is - incorrectly - not enabled, some current starts to flow into VDDA when ADC is enabled.
As usual voltage regulators can only source current, not sink, this may result in unexpectedly elevated VDDA voltages. In smaller packages, where VDDA is bonded together with VREF+, this in turn results in unexpectedly lower ADC readings.