I've flown on Wizz Air from Schengen to UK and remember there was a mandatory passport check for non-EU citizens, which had to be done at the check-in desk.
Is there also a mandatory passport check on Schengen and internal flights?
The question is important for planning tight connections on two bookings.
(See the related Ryanair question Flying with Ryanair as a non-EU citizen for what these kinds of passport checks look like.)