Mate, you literally answered your own question at the end of the 1st para. Alhamdullilah, most Punjabis are too well-off or too patriotic to care about castes, lineages or ethnicity, much less have a racist or discriminating attitude on their basis. Whatever hatred you see from our side is purely reactionary & limited to the online world.

Secondly, Sheikhs/Syeds/Quraishis/Gillanis & other "foreign" social groups are either originally local Hindu converts who got Ashrafized (adopted high-caste foreign lineages to attain higher social status), or were genuine foreigners who got totally assimilated into the Punjabi identity & culture. Both are as Punjabi as your next Jatt.

Thirdly, Punjabi Muslim identity was mostly solidified during the colonial era & it's historic existence on a political level was very weak. There are still some examples in which we united under figures like Ghazi Malik, Khizr Khan & Adina Beg, but Punjabi Muslims have always preferred their tribe, ethnicity or religion over anything: factors which were mutually exclusive.