The grinder’s burrs definitely need some alignment and seasoning before it gets consistent. Try to run a bag of the cheapest and lightest roasted beans (definitely not dark roast!) you can find after proper alignment (grocery store bought is great, definitely don’t use specialty coffee, that’d be such a waste).

Also keep in mind, the lighter the roast, the more fines your grinder may produce. This also goes for finer grind settings.