Our windows are very clean and we see absolutely no "smearing", even when the sun shines on the windows. When I used to clean the windows by hand, I often had smear marks. I have much better results with the robot. Please note that the wiping pad must be well moistened with water - see instructions.
So far, we have only used the original cleaning agent and, despite the relatively high price, I have no desire to experiment with other liquids - the results are too good for that.

Unfortunately, this is exactly what I have experienced. There are actually smear marks on the discs, which you can see very clearly when the sun shines on them. I did everything correctly in the application, so that can't be the problem. The Ecovacs cleaning agent is also only suitable for outside use to a very limited extent, as you can see dried raindrops very clearly: It has no beading effect at all, as is sometimes the case with other window cleaners. So far, however, I have not dared to use any other cleaning agent as I am not sure whether it is compatible with the appliance.