It's a common misconception that titanium dioxide is the culprit to flashback (the white face effect) .
Titanium Dioxide is a white mineral powder that is present in ALL foundations . It is an essential part of foundation, it is mixed with other coloured oxides to produce the skin colour of a foundation. In other words you can't buy a foundation without it containing titanium dioxide.
In some foundations excess titanium dioxide is added and combined with zinc oxide to create a cheap SPF within the foundation. It's this combination that is problematic . It works as a sunblock so it reflects all light away from the skin , protecting you from harmful UV rays but unfortunately causes flash back with flash photography (all light is reflected back and you see the white base of the titanium dioxide and zinc oxide mixture). This effect does not happen with photos taken in natural light.
With advancements in technology this phenomenon is starting to fade out as more and more cosmetic companies are using sunscreens instead of sunblocks in their foundations. Sunscreens work by disrupting the harmful uv wavelengths into unharmful wavelengths , nothing is reflected so no flashback occurs. This is why a foundation can contain even a high SPF these days and yet cause no flashback
So in a nut shell , you don't have to avoid SPF in a foundation , just watch out for a high content of titanium dioxide (it will be high up on the ingredient list ) combined with zinc oxide