Well so far everything on lemmy has run on the goodwill of instance owners, lemmy maintainers, and app developers working for free. Sync as far I can tell is the only thing so far to bring an openly capitalist approach to lemmy, and it depends on the free hosting that instance owners are providing. I don't have any problems with people wanting paid for their work. However, I can see how it's a little jarring to see an app charge such a subscription fee while some big instances are struggling with hosting costs and likely pulling in much less in donations.