Well my floors are also spotless, so I can confirm that it picks up everything that's there to pick up, don't forget that the roborock mops also, so there's really no chance for any leftover dust or dirt (all dirt picked up by the mop gets washed by the dock and flushed down the laundry room drain automatically so there's a portion of dirt that doesn't even contribute to filling the dock's bag). And now with a cat it picks up all the cat hair and when it empties I can hear a clump of it being emptied into the dock. I think it has more to do with the S7 ultra dock bag being 3 liters, and with how powerful the dock's emptying vacuum is because it seems to compact the fuzz it's collected quite a bit. This one's bag looks tiny on comparison, but they don't give the dimensions. The roborocks is 6"x6"x5" approximately (dimensions vary a bit from listing to listing but most listings are right around 3L based on the given dimensions).

I mean just take a look at the video on the matic website, it looks like the bag is smaller than a person's hand. The roborock is 1.5 times the size of a 2 liter soda bottle. That's a huge difference.