I don't think they're hiking it up to introduce an ad-subsidized tier.
I do think that their operational costs have gone up significantly. One of the places where costs may have gone up are their data centres, especially if they are in regions where it is fossil fuel dependent, simply because DCs consume a lot of electricity: power to equipment, cooling (sometimes heating), generators, equipment maintenance, employee equipment. Add on top the employee salaries, benefits, legal costs, etc.
It sucks to say, but it's a vicious cycle