I don’t feel uncomfortable seeing anything really.
It just doesn’t make sense to me that, as a society we consider breasts to be “private parts”, which are not to be displayed in public (even if it were an extremely hot day a woman probably wouldn’t want to just walk around topless in most public settings, and probably wouldn’t even be allowed to). But then we change our minds as soon as there’s a baby drinking from it (especially given that breastfeeding privately or bottling breast milk from beforehand is not particularly difficult).
I don’t really see the logic in terms of why they’re absolutely private in one situation (even to the point of inconvenience) but not the other.