I don't think most people would consider direct payment to reputable companies like Epic to be a particular security risk. I don't think most realize why they can't subscribe to Spotify from their iPhones, they think it's simply not implemented.
The thing is, Apple now holds a tremendous amount of power over a large set of the population. All the comments saying "just buy an Android" ignore the simple fact that you buying an Android does not change the fact that a significant portion of the market is elsewhere.
I'd be more OK with this if Apple was OK with displaying a 30% Apple tax on checkout. But the fact that they prevent apps from showing it and actively try to conceal it shows that they know most of their customers would ask questions about it, at the very least, likely question if the "benefits" they get in return are worth it.