Speedometer difference up to maintenance

Moin I have the BP now almost 2 years. There was already in the first year a difference of driven kilometers and the indicated in the display km to maintenance. So: 12000km drove, but only 4000km rest until maintenance. In this second year this is even more drastic. 13000km drove and have still rest of almost 1000km. Well in two weeks I have to anyway for maintenance, but what is that supposed to do? I would at least understand something if I would drive mainly short distance. But with me is e I don’t know how those values come to these values. I assume that the oil is being monitored. But what else? And what does that actually mean? That would mean in the future, all 10000km of oil changes like tens of years ago. Can’t be, especially since I also have the oil of Mazda with the gold particles in it. What does it look like with you? Many greetings