I bought a Kia Seltos 1.5D AT in January 2024 and have driven 30,000 km. After the recent 30K service, the DPF failed. The service centre will replace it under warranty, but I want to know whether all BS6 diesel vehicles face DPF issues or if it’s mainly seen in Kia diesels. Also, can this problem occur again in the future, even though around 25,000 km of my usage is highway driving?

This isn't a problem with Kia cars alone. All engines equipped with a DPF have to undergo a DPF regeneration cycle regularly. This typically happens automatically when the exhaust temperature is high enough, typically when the car is driven for 20 to 30 minutes at speeds around 60kph and above, typical of a highway drive. 

If this does not happen, the car will alert you via the instrument cluster, and you will have to conduct a complete cycle as instructed. The failure can occur if the warnings are ignored or due to some manufacturing defect. In any case, it is good that the dealer is replacing the DPF under warranty. 

Going forward, if you have frequent short trips, try and include one 30-minute highway drive at least once a week. Also, avoid long idling periods, make sure you pay attention to all alerts - in case you have ignored any - and fill fuel from a reputable pump.