These are incremental changes to baggage and seat fees, building on what they already did recently. Instead of two bag fees (online and at check-in), there's now a third as online check-in and airport check-in have been separated.

Paying for exit row seats during check-in was already in effect, but now they're adding Preferred seats to that as well. As per the WestJet Agent site, Preferred and Exit seats will continue be free during check-in if there are no Standard seats available (eg. the flight is full): Updated seat selection and bag fees.