Don't know about any other ethnicity but have experience with Punjabis in different walks of life.
They have a very condescending attitude towards Pashtuns and borderline racist. You can tell how they show Pashtuns in tv, media as some dumb people, that's pretty much how they see us in real life.
Whenever going through army checkpoints in Peshawar/KPK, we would pray it was some Pashtun because Punjabis would just act cold-hearted and make you suffer.
Of course not everyone is like this, had friends in school and in university, few girl "friends" who acted okay.
My impression is once they get to know us, they drop their preconceived notions about us. For many who haven't interacted with us except at bare minimum, their attitude is really bad. Pakistani media is really crap. They show Pashtuns as really dumb fcks who can't speak Urdu and are always shown as comic relief or fighting wars like the only two things we're good at, that has to leave an impression.
The positives i would say is they're smart people, well educated and going places.
The media impression of Pashtun’s has a lot to blame for this. Both in terms of portraying them as simpletons or extremists. Being from Karachi and a UP family one hears the negative stereotypes.. but then the history with land grabbing mafia from MqM and AnP going back to Gohar Ayub’s racism and oddly those of the Brown “Sahib” urdu-speaking/central Punjab migrants that formed the bureaucracy added to the cross hatred. This was added to by the fearful and crime ridden reputation of Pashtun areas in Karachi including stories of “glueing eyes of Mohajirs( although large percentage of this were the tribal economic migrants and especially the Afghan refugee population which was recruited into ANP proxy wars(a different and vast subject altogether on Karachi dynamics).
However, having lived in Peshawar for two years and having love interests there for a while, all the stereotypes were dispelled... at least in terms of their uniqueness of “simpletons and terrorists”. I did encounter racism in Peshawar with one of my professors openly declaring in his Pakistan studies class “Mohajir bohat khabees qaum hai”.. but oddly full of effusing praise for my father because he was well known in the high end social circles of Peshawar.
Yet, even with simpleton encounters ( such as that of servants walking cycles to fetch bread since they did not know how to ride one but as we had suggested taking it.. he did.. ) and us unknowingly venturing out for a picnic right near an area where a TTP attack had taken place and the army had vacated.. the majority of these stereotypes apply to ALL ethnicities.
I have not encountered another ethnicity in Pakistan more focused on education when they get down to it or loyal. A lot of it has to do with culture and lack of access to the facilities the state has denied historically.
The point of this reply is that having lived in 3 provinces of the country in multiple urban and rural areas.. and not in sheltered military bases; I find that all ethnicities have mostly positive attributes in different spheres to contribute and the negative aspects are generally more shared.
The greatest issue is lack pf exposure to a multi-ethnic environment from a young age which even in later life leads to inherited prejudices.
The true solution to this is increased urbanization (not exactly ideal) or encouraging movement and tourism between areas.
The biggest problem in Pakistan will remain ignorance; be it of science, proper religious education, culture or ethnic relations. Unless you know and/or experience a lot early on and then be taught early to decide on merit what is right and wrong.. you will continue to harbor misconceptions and ill will.
Finally, what is important is the lesson that while horrible mistakes have been done by all sides.. some more than the other; the current generation should not continue or be punished for them other than being taught their evils and told to avoid them. The focus on the eye for an eye is why we still see racists on this forum running amok because that is what they have been taught by families or the social environment they live in.
Until each of us let’s go, forgives and starts looking to forge trust.. Pakistan will not remain as these sins pile up against it.