(im a muslim) why do some Muslims judge other Muslims for their faults or what they are doing?

like i see some Muslims criticize how Muslim women dress now like for example they see a picture of a muslim girl whos wearing hijab and long shirt with jeans or a girl with a long skirt and kinda tight shirt and i saw one person said something like that they think that those girls who do that are the worst of the creation i think its really mean and the people who say that should let only Allah judge and they should be nice only Allah should be the judge of that