You think it's brewing? Have you tried visiting other provinces and asking other ethnic groups what they think of Punjabis or Pakistan? This isn't just Baloch or Pashtuns. You'll find hatred in Gilgit Baltistan, AJK, and even Sindh. Ask Bengalis in Bangladesh who they blame for the fall of East Pakistan?
This happening not because of ordinary Punjabis living ordinary lives. This is happening because the army establishment has been overwhelmingly Punjabi and so has the ruling power structure. Figure heads from different ethnic groups won't solve the problem and is seen only as a band-aid.
This is also happening because KPK, Balochistan are far less developed than Punjab due to most of power structure being from Punjab and consuming more of the resources since votes from other provinces didn't matter. PMLN has used the center, which is usually guaranteed because Punjab, to fund projects that benefit Central Punjab at the expense of the country. Just to give you one example, Orange Metro line, costing billions of dollars, was built to benefit Lahore instead of building ML-1 rail which would have benefitted the entire country.
Remember how CPEC originally was supposed to run through western Pakistan to Gwadar, was changed by PMLN to run through Punjab instead? PTI focused on ML-1, uplifting Balochistan, ex-FATA, interior Sindh so the disparity in western half of the country can be resolved, along with militancy and separatism. In contrast, people here can remember Shehbaz Sharif literally asked TTP to spare Punjab, as if the rest of the country was acceptable loss.
If you want this hatred to stop, then try uplifting the other parts of the country and building much more inclusive government where every ethnicity has a share. Ironically, Zardari passing the 18th amendment was beneficial since it gave the provinces the ability to uplift themselves. Had something like this existed before 1971, we could avoid Bangladesh like issues.