Let's face it. How many of us have actually contributed enough to any FOSS projects to demand for free and premium services. I personally would rather donate to a FOSS app instead of paying Sync, but it's unfair to judge Sync for having ads and trackers when the option of removing them is there. There's nothing wrong with any dev wanting to make a decent living or even more than that, as long as they don't go overboard and are honest about it.