It is in dispute, what is not in dispute is killing of sikhs in delhi incited by party members of than ruling govt.
Sikh's are not in minority in punjab they are in majority or do you mean punjab region itself is discriminated by federal govt?
Also you need to make distinction between sikhs(followers of religion) and khalistani(people demanding separate statehood). In punjab there was genocide against minority(hindus) by khalistanis NOT sikhs(they were protectors and some even laid their lives against it) but it is inconvenient to talk about so doesn't get much mind share.
I generally refrain talking about india because whenever i try to dig deeper it becomes more and more complex that i simply give up on finding what is true. What i do know is to treat popular narrative with skepticism.