Privacy is a marketing angle right now for sure. I hate seeing companies like apple advertise to the vague privacy concerns of the general public. Companies like Proton are also making money based on privacy concerns.
As far as I've seen, FUTO's approach is to fund and support independent developers who have a high skill level and well thought out piece of software. They focus on software that is Open, or source available for auditing and viewing purposes, privacy respecting and free of any kind of advertising. They also are pushing for a new culture of payment to these developers that is not a donation to support, but a purchase to use. They don't insist on the purchase though, you can use any piece of FUTO sponsored software free of charge indefinitely.
Why do you think you aren't really buying it? Is it because they allow you to run it without paying money for it?
I don't think the definition of "purchasing" software should be defined by whether you can run the service without paying or not. I think it's best defined as paying money for something that you like and want to exchange value for. In my book that's nothing near a dark pattern, as I can't imagine anyone being confused by it, let alone mistakenly believing there is missing features that they won't get until they buy.